geog 102 exam 3
Mid Atlantic Ridge
divergent boundary in the middle of the Atlantic Ocean
False
A transform boundary creates mountains.
volcanoes in the U.S.
52 volcanoes have erupted in the U.S. in the last 200 years, most of them occurring in Alaska Between 1914 and 1917, Lassen Peak in Northern California erupted All the volcanoes in the U.S. are closely monitored by the United States Geological Survey
Slide #2-Reservoirs
96 people died building Hoover Dam. The Hoover Dam was started in 1931 and completed in 1936. The reservoir behind Hoover Dam was named Lake Mead. The Glen Canyon Dam (which is near the border of Utah and Arizona) started holding water in 1963. The reservoir behind the Glen Canyon Dam was named Lake Powell. A large waterfall on the Colorado River is now buried under Lake Meade. Upstream of the Aswan Dam in Egypt (which was constructed across the Nile) impoundment of the river has resulted in the loss of numerous classical Egyptian artifacts. A lot of the water trapped behind the Glen Canyon Dam percolates into the ground because much of the bottom of the river is porous Navajo sandstone. Many of the canals that carry water from the reservoir to farmland are simply ditches excavated in the soil or bedrock and they leak profusely. There is a growing recreation and tourism industry around Lake Powell, as previously inaccessible desert scenery is now reachable by boat. The valleys upriver got flooded with river water and become part of the reservoir.
Alluvial Deposits
Diminished speed is the result of a change in stream gradient or when the channel widens or changes direction When the stream slows deposition will happen Rock frequently collide with one another becoming both smaller and rounder
Why was the Haiti earthquake, despite being roughly the same power, cause so much more death and destruction than in Japan?
Haiti is very poor so the infrastructure collapsed very quickly
Slide #6-Volcanic Activity
If the volcano has not erupted in a couple hundred years people are lured into a false sense of security. People tend to think that an "active volcano" means that it is currently erupting. 80% of volcanic activity is located beneath the ocean. Remember that the Mid-oceanic Ridge is a line of volcanoes on the ocean floor that constantly spew out lava.
Slide #38- China Earthquake of 1556
Mountainous areas don't fare well in earthquakes. In Peru in 1970, a 7.8 magnitude earthquake caused an avalanche that obliterated an entire mountain village. Slope failures block roads that can increase the death toll by hampering rescue operations.
Is economic collapse a local, global or national effect?
National
Where is Iceland in relation to The Uk, Greenland and the USA?
Northwest of the Uk, East of Greenland and Northeast of the USA
Which scale measures strength?
Richter scale
continental drift
Scientists believed that the continents and oceans were in a fixed position Alfred Wegener put together the first comprehensive theory of continental drift in 1915 Wegner believed that the continents moved in the past and that they continue to move
Slide #13-Competence
Some rivers descend one thousand feet per mile. Some rivers only fall 10 feet per mile. The Amazon River drops ½ inch per mile. The larger the cross section of the river, the lower the gradient. Early explorers who visited the Grand Canyon said they were kept up at night by the thundering sounds of the river and rapids. Large pieces of rock material were be moved along by the Colorado River before the Dams were built.
A piece of crust which has been in collision along a convergent boundary and becomes accreted to a continent
Terrane
stream flow
The amount of friction is determined by the width and the depth of the channel Water in a narrow and shallow stream channel with a rough bottom moves slow Water in a wide and deep stream channel with a smooth bottom moves fast
Why was the Eyjaffjallajokull eruption so bad for the UK and most of Europe?
The ash cloud drifted over Europe and closed the air space
China Earthquake of 1556
The loess region has numerous hills composed of windblown silt and fine sand that has very little cohesion The soft sand and silt caves vibrated apart and 830,000 people died In 1920, another earthquake in the region killed over 100,000 people
Earthquake
When the earth's tectonic plates move, we call this a BLANK.
Slide #26-Continental/Continental Tectonic Plate Convergence
When two continental tectonic plates collide huge mountain ranges form like the Himalayas and the mountain ranges in Afghanistan, Iran, and Pakistan. No subduction takes place because the continental crust is too thick to be subducted. It is like taking a piece of paper and pushing both sides together. The paper will pop upward in the middle. No volcanic activity exists because there is no melting taking place. To get volcanoes, a tectonic plate must be subducted and melt. Earthquakes on the other hand happen very frequently near Continental-Continental tectonic plate convergence boundaries.
Slide #11-Exogenic (External) Processes
Wind is not strong enough to dislodge firm moist, clay rich soils or soils bound by dense plant cover. Plant cover also slows down the speed of the wind near the surface, though wind can prune and shape vegetation. A huge F-5 tornado can destroys building and vegetation but it doesn't destroy actually destroy a landform. A tornado isn't going to erode a mountain or cave. During the dustbowl people were vomiting up dirt and being blinded by it. No matter how they tried to pack door frames the dust would still get in. The sand storm on the slide was traveling at 60 mph and was about 3,300 feet in height. It passed over in about 45 minutes leaving a thick layer of dust in its wake.
island
a body of land completely surrounded by water
peninsula
a body of land that is almost completely surrounded by water but its still connected to a mainland (thats what makes it different)
island arc
a chain of volcanic islands formed at an ocean-ocean convergent boundary
volcanic arc
a chain of volcanic mountains formed at an ocean-continental convergent boundary
plain
a flat lowland with very little hills , no mountains and it is very plain. good for agriculture . most people live on plains. Plains typically occur at low elevations
mountain range
a group of mountains, has steep sides and pointy tops, the older it gets the more rounded the tops get
Midocean ridge
an underwater chain of mountains.
What is the scale most commonly used to measure earthquakes
is Richter
lake
is a body of water that is completely surrounded by land, it doesn't connect to anything.
capacity
Is a measure of solid material that a stream has the potential to transport It is measured by the volume of material passing a given point in the stream channel during a certain interval Capacity may vary significantly during different seasons
competence
Is a measure of the largest particle size that can be moved by a stream Depends on flow speed Streams that normally transport only sand grains normally can move boulders during a large flood Determines good streams for hydroelectric power
Los Angeles Aqueduct
LA bought 95% of the farmland and 85% of the buildings in Owens Valley and has even drilled wells in the valley Teddy Roosevelt wanted another big city on the poorly defended west coast The aqueduct was started in 1907 and completed in 1913
Slide #29-The Rearrangement of Pangaea
The earth is 4.6 billion years old. The continents as we know them today were unrecognizable throughout most of earth's history. 250 million years ago, there was only one continent and one ocean. About 200 million years ago, Pangaea began to break into two massive pieces and then into a number of smaller pieces. The plates became separated and started drifting into various directions like ice floating on a pond. Antarctica is the only continent that remained near its original position. India is the continent that moved the fastest. 135 million years ago, continental fragmentation was well under way. The North Atlantic Ocean was starting to open up. The South Atlantic began to separate South America and Africa. The Mediterranean Sea began to close as Africa rotated towards Asia. 65 million years ago, the North and South Atlantic Oceans joined. South America was a new and isolated continent that was rapidly moving westward. The Andes were growing as South America overrode the Pacific Ocean basin. Today, South America has connected with North America. North America has separated from Europe, Australia has split from Antarctica, and India collided with Eurasia to thrust up the Himalayan Mountains. All continents except for Antarctica are still in motion. Africa is splitting along the East African Rift Valley and slowly rotating counterclockwise. 50 million years in the future, Australia will straddle the Equator. Africa may pinch the Mediterranean shut and east Africa will become a new large island like Madagascar. The Atlantic will widen and the Pacific will shrink.
Slide #11-Stream Erosion
The erosive capability of stream flow is also significantly enhanced by the abrasive tools it picks up and carries along with it. Just as particles on a piece of sandpaper can wear away wood, so to can sand and gravel carried by a stream. Boulders cause water to act like it is going through a maze. The boulders cause the water to become turbulent. It goes forward, sideways, and sometimes even backwards before going straight. Channel roughness found in high gradient rivers decreases the flow.
Mt. St. Helens is which type of volcano
composite
The Himalayan Mountains were formed by which type plate boundary
convergent
two major endogenic forces
earthquakes and volcanoes this builds up the landscape.
A tall and rocky piece of land that protrudes out from the rest of the coastline
headland
Geomorphology
is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or near the Earth's surface.
What volcano has the lowest viscosity lava
shield
When the sun, moon, and earth are in alignment is produces _______ tides
spring
A desert streambed is called a
wash
exogenic forces
wears away the landscape. 3 major; running water; glaciers; wind
Horst & Graben (Tension)
A Horst is an elevated block of land between two parallel faults A Graben is a block of land bounded by two parallel faults that been downthrown Horsts and Grabens often occur side by side like in the Basin-and-Range area of the desert southwest
What state has the greatest number of volcanoes
Alaska
Where do earthquakes occur in terms of plates?
Along plate boundaries
Why does friction build up along the plates?
Because the movement is not smooth
cinder cone volcanoes
Cinder Cones are the most common type of volcano They are cone shaped peaks built by the pyroclastic material that is ejected from the crater Cinder cones don't grow very large because they have a very short life span
What is the plate boundary called where two plates move away from each other?
Constructive
Slide #5-Endogenic (Internal) Processes Tectonic processes are associated with faults and earthquakes.
Endogenic Processes usually operate very slowly, but can sometimes happen quickly. The Northridge earthquake in 1994 raised the elevation of the San Gabriel Mountains by a foot. The San Fernando earthquake in 1971 raised the elevation of the Santa Monica Mountains by 6 feet. The Loma Prieta earthquake in 1989 quake raised the elevation of the Santa Cruz Mountains by 31 feet. The picture on the slide is from Montana. An earthquake in Montana in 1959, displaced the land by 23 feet in a matter of seconds. The cliff in the picture was created by the earthquake. That earthquake caused a landslide that killed 28 campers near Yellowstone National Park. Volcanoes will erupt and earthquakes will occur no matter what the weather is like. Volcanoes and earthquakes are in no way influenced by the temperature or amount of precipitation in a particular location. Volcanoes can erupt in places as warm as the Philippines and Indonesia and as cold as Iceland and Antarctica.
Exogenic Processes
Glaciers shape both mountains and flat areas Glaciers are very slow moving rivers of ice that move under the pressure of their own weight and the pull of gravity Glacial ice currently covers 11% of the Earth's land area, but in the "Ice Age" it covered 30%
Foreshocks and Aftershocks
If you have a foreshock, after three days the risk of major earthquake is almost gone The day after the main earthquake has about half the aftershocks of the first day Ten days after the main earthquake there are only a tenth the number of aftershocks
1985 Mexico City Earthquake
Large buildings have been constructed on weak, water- soaked lake-floor sediments An 8.1 magnitude earthquake centered in Acapulco was followed very shortly by a 7.5 aftershock 15% of the buildings in Mexico City completely collapsed
Los Angeles Aqueduct
Los Angeles annexed the San Fernando Valley to store excess water The amount of irrigated land in the San Fernando Valley increased 25 times between 1913 and 1918 Until the late 1970s the aqueduct was still getting dynamited sporadically by the residents of Owens Valley
Slide #7-Exogenic (External) Processes
Running water exists almost everywhere on earth except in Antarctica. The Grand Canyon is pictured on the slide. The Grand Canyon was created by the Colorado River cutting into the Colorado Plateau. The erosion caused by the Colorado River created a mile deep gorge.
False
T or F California is an example of an island arc.
True
T or F Indonesian Islands are an example of an Island arc.
True
T or F Japan is an example of an island arc.
True
T or F You will find earthquake activity in a continent to continent convergent boundary.
True
T or F, a subduction zones would have earthquakre activity.
Slide #22- Los Angeles Aqueduct
Teddy Roosevelt thought Japan was bristling with expansion and dirt poor in resources. America was vulnerable on its unpopulated western flank. Teddy Roosevelt in 1901- "The Western Half of the US would sustain a population greater than that of the whole country today if the water that ran to waste were saved and used for irrigation." Right after the aqueduct was built, the following 10 years were unusually rainy and the aqueduct water was not needed because the groundwater table was recharged and LA River was flowing. Santa Monica Blvd changed from a dusty rut to a palm tree lined oasis. This gave the impression that Southern California was not that dry. The movie "Chinatown" came out in the early 1970s and it is about the construction of the Los Angeles Aqueduct. Chinatown is considered "historical fiction", meaning that most of the events in the movie are fictitious, but some events are real.
Slide #17-Origin of Continents and Oceans
The Mesosaurus dinosaur only lived in freshwater environments. Critics said that the Mesosaurus must have migrated across land bridges that were originally connecting the continents, but that the land bridges had later collapsed into the ocean. Mountain ranges in Greenland, Scandinavia, and the UK match up with the Appalachian Mountains in the Pangaea Formation.
Slide #19-Lava Dome
The lava that is emitted is too thick to flow very far. Lava domes can develop within the craters of composite volcanoes when thick lava moves up into the vent. Shortly after the eruption of Mt. Saint Helens a lava dome began to develop which is now over 1,000 feet tall. Mono craters located to the east of Yosemite are lava domes. Lassen Peak in Northern California is the world's largest lava dome.
Slide #16-Origin of Continents and Oceans
The seeds of the fern plant (called Glossopteris) are too large to be carried by the wind across the expanse of the present day ocean. The Glossopteris flourished in colder climates and would have not survived in the warm present day regions where the fossils are found. They are found in Australia, India, Africa, and South America.
Pyroclastic Flow
The violent eruption of a composite volcano can lead to a high-speed avalanche of searing hot gasses, ash, and rocks (volcanic bombs) Pyroclastic materials can reach altitudes of 20 miles in the atmosphere A pyroclastic travels down a volcano at 125 miles per hour
volcanoes
Volcanoes are temporary features on landscape A volcano is active if it has erupted once within historic times and will likely do so again 2-3 volcanic eruptions per decade are major disasters 75% of all volcanoes are located on the coastline of the Pacific Ocean
Slide #2-Mount St. Helens
Within minutes 1,300 feet of the mountain had disappeared by being blasted into the sky and down the mountainside. The lateral blast (north) burst outward at 250 miles an hour and the forests, lakes, and campsites for nearly 20 miles away were obliterated by the force of the blast. The materials ejected from the blast were 570˚. Hundreds of homes were buried or badly damaged. The heavy weight of significant ash accumulates on roofs and can cause buildings to collapse. Six feet of ash fell on the local area and residents experienced midnight like darkness at noon. Ash fall from Mt. St. Helens was being recorded as far away as Minnesota and Oklahoma. People as far away as Northern California and Canada heard St. Helens explode.
A well developed sandbar that partially closes off an inlet
a spit
Convergent
A BLANK boundary creates mountains.
Divergent
A BLANK boundary creates new ocean floor.
Alfred Wegener
credited with the theory of Continental Drift
Harry Hess
credited with the theory of Plate Tectonics
What does the Mercalli scale measure?
damage
An example of a social impact of an earthquake is?
death
trench
depression formed at a subduction zone
Which plate boundary are composite cone volcanoes found on?
destructive
Pacific Ring of Fire
A major volcanic zone which is found along the Pacific ocean and travels all the way from South America, to North America and along Asia.
What instrument can predict earthquakes?
A seismometer
Slide #12-Channel Flow
A small, steep mountain stream is actually moving slower than a large, lazy looking river. The Mississippi River is moving 1mph at the headwaters and 3mph at its mouth. Vegetation growing on the side of the streams banks can also hinder stream flow near the banks.
Anticline (Upfold)
An anticline is an arch like fold, with the limbs dipping away on either side of the of the axis of the fold Anticlines typically produce ridges Oil and natural gas collects in upper portions of anticline folds in rocks such as sandstone
drought in the western U.S.
As of 2006, the river is at only 50% capacity and engineers estimate it will take thirteen consecutive seasons of normal snowfall to reset the system completely Hydroelectric power at Hoover Dam is now at 50% capacity and it is getting worse
Pacific
California borders the BLANK plate and the North American Plate.
The East African Rift Valley is formed by which type of boundary
Divergent
What word is used to describe how often an earthquake occurs?
Frequency
plateaus
Is basically an elevated plain, similar to mountains, except fIt should be terminated on a least one side by a steep edge that marks the boundary with the lower elevation Erosion can make a plateau look like a series of hills in areas that get a lot of rainfall lat on top, it has steep sides (plateau flato)
Mt. Rainier
Is the tallest mountain in the Cascades and last erupted in the 1840s Has the largest glacier system in the "lower 48" 100,000 people live in an area that could be affected by the mudflows produced by Mt. Rainier Many houses are built on old mudflows
Arc
Japan is an example of an island BLANK.
colorado river
One of the few exotic rivers in the world Drains parts of seven states 9 dams have been built on the Colorado River The dams protect settlements from floods, keep the water at a constant level, and generate inexpensive electricity
Slide #38-Anticline (Upfold)
Petroleum Geologists know that oil and natural gas collect in the upper portion of anticline folds in a permeable rock like sandstone.
plains
Plains are good for farming because tractors, combines, and other farm machinery only work on level land. Plains typically have much better soils than mountains. You don't have many large cities located in mountains. Large cities are usually located in the plains areas because building on steep mountainsides is difficult and dangerous. Some plains can be located at high elevations. The High Plains in Colorado is 5,000-6,000 ft. in elevation.
Is educating the public predicting, preparing or protecting from earthquakes and why?
Preparing because people will know how to behave in an earthquake
San Andreas Fault
Southern California sits on the boundary between two of the earth's major tectonic plates The two tectonic plates move past each other between 2-3 inches per year Much of this motion is accommodated from time to time by a sudden slip in the fault
False
T or F A divergent boundary would create mountains.
colorado river
The Colorado River starts at 13,000 feet and flows down to sea level which is the largest drop by any river in the U.S. A desalination plant in Yuma, Arizona opened in 1973 because the river had 77% of the salt content of ocean water by the time it got to Mexico
What is the definition of a Political effect?
The impact of a hazard on the government
Slide #29-San Andreas Fault
The San Andreas Fault unfortunately does not produce small earthquakes. Luckily geologists believe that an earthquake larger than an 8 magnitude could not occur on the San Andreas Fault. Very large earthquakes are associated with convergent tectonic plate boundaries, not transform tectonic plate boundaries.
Gondwanaland
The continents of Africa, South America, India, Australia, and Antarctica when all the continents were a single landmass.
Laurasia
The continents of North America and Eurasia when all the continents were a single landmass.
What do you call the point on the ground above the focus?
The epicentre
Slide #3-Krakatoa
The island of Krakatoa was 1,500 feet in elevation before the eruption and is now is 90 feet under the ocean. The Greek island of Santorini is pictured on the slide. A city there was buried to a depth of 230 feet below the ocean during a huge volcanic eruption. The island was circular before the eruption occurred. The eruption happened in 1628 BC. Plato's description of the "Lost City of Atlantis" is very similar to the city that existed on Santorini before the eruption. Many people speculate that is the location of the "Lost City of Atlantis". Santorini erupting darkened the skies in the Mediterranean Sea area for days. Some believe that this was the event that is described in the Old Testament as retribution against the pharaoh. It happened in 1645 B.C.
San Andreas Fault Movement
The northern section of the fault was displaced 21 feet by the 1906 San Francisco earthquake The 1857 Fort Tejon earthquake displaced the southern section of the fault by 31 feet The 1989 Loma Prieta quake displaced the northern portion of the fault by 3 feet
lava
The speed at which lava flows is based on the viscosity of the lava The more viscous the material, the greater the resistance to flow When lava hardens to rock it eventually weathers and releases nutrients into the soil which dramatically increases the soil fertility
Slide #16-Shield Volcano
They are built up by layer upon layer of solidified lava flows. Some shield volcanoes are high, but never steep sided. They are much broader in size than high. Size varies greatly. Sometimes the low viscosity lava rises to the surface through long fissures rather than the central crater. It reduces the pressure because it allows the gas to escape. You can get high fountains of lava from shield volcanoes. Fissure flows can produce vast, flat lava plains. Usually shield volcanoes feature both fissure and crater lava flows.
Oceanic crust is (thicker or thinner) and (denser or less dense) than continental crust
Thinner; denser
Japan
This country is an example of island arc.
Mid Atlantic Ridge
This is an example of a mid ocean ridge.
Western Coast of South America
This is an example of a subduction zone at a convergent boundary between a continent and an ocean.
East Pacific Rise
This is an example of sea floor spreading at a divergent boundary.
Why are there computer controlled weights on the tops of earthquake proof buildings?
To counteract the sway of the building
The plate boundary associated with lateral slippage and the San Andreas fault
Transform
transformation boundaries
Two plates slip past one another laterally Crust is neither created or destroyed Is associated with a great deal of seismic activity that produce significant, but not huge earthquakes The San Andres Fault is located on a transform boundary
Volcanic Gasses and Ash
Water vapor makes up the bulk of the gas emitted Sulfur dioxide and carbon dioxide are also emitted Vehicles stall when ash clogs the air intake valves in engines Enough ash can collapse the roofs of buildings
Origin of Continents and Oceans
Wegner believed that a massive super continent (named Pangaea) existed 250 million years ago Portions of African and South America fit together like a jigsaw puzzle Coal deposits would be continuous on both sides of the Atlantic if the ocean did not intervene
The North American plate is moving very slowly towards the
West
Sea Floor spreading
What type of process is created by a divergent boundary.
Subduction
When one tectonic plates dives under another, it is called BLANK.
mountain range
formed at a continental-continental convergent boundary
The Pacific Plate is moving about 2 inches a year in which direction
northwest
Large rocks, ash, hot gasses, and lava ejected violently during an eruption forming a cloud
pyroclastic materials
The San Andreas is which type of fault
strike-slip
river
surrounded by land on both sides the difference between a lake and a river is that the river is more narrow and skinny and usually connects to another body of water.
What is the only Hawaiian island to have any current volcanic activity
the Big Island
The area on the surface directly above where the earthquake occurs
the Epicenter
The depth at which the fault slipped during an earthquake
the focus
subduction zone
the more dense plate us pulled into the mantle under the less dense plate
Rifting
the process by which Earth's crust breaks apart; can occur within continental crust or oceanic crust
Lithosphere
the solid, outer layer of the earth that consists of the crust and the rigid upper part of the mantle
Sea Waves triggered by an earthquake or another sea floor disturbance
tsunami
What is the type of waves earthquakes give off?
Seismic waves
Plate Tectonics
the theory that explains how large pieces of the lithosphere, called plates, move and change shape the topography of the earth.
Convergent
this type of ocean to ocean boundary would create a trench.
What is a positive impact of a volcano?
tourism
convergent boundary
when two plates come together
transform boundary
when two plates grind past each other
divergent boundary
when two plates pull apart
What two plate boundaries can volcanoes occur on?
Constructive and destructive
Which plate boundary are shield volcanoes found on?
Constructive plate boundary
What are some features of a shield volcano?
Gentle slopes, frequent eruptions, formed by many runny eruptions, slopes of solidified lava
What are some features of a composite cone volcano?
More viscous lava, less eruptions but more explosive, steep sides, pyroclastic flow (Hot steam, ash, dust, rock)
False
T or F there are only two types of convergent boundaries.
False
T or F, a subduction zone occurs where to plates move away from each other.
Volcano
The vent on the earth's surface through which magma and gases are expelled is a called a BLANK.
Theory of Continental Drift
Theory that continents move due to centrifical force
Volcanoes and Earthquakes
_____ and _____ are features found at an ocean to continent convergent boundary.
Convergent boundary
boundary between two colliding plates, often associated with mountain building ocean trenches and volcanic islands
Transform boundary
boundary between two plates that are sliding past each other sideways.
pangea
large supercontinent that existed 250 million years ago
oceanic crust
earths crust located under the ocean
continental crust
earths crust made of land
rift valley
formed when two plates pull apart and land falls downard
Asthenosophere
is the layer of the upper mantle composed of low-density rock matterial that is semiplastic,like putty.
plates
large pieces of earths crust that move due to convection currents
sea floor spreading
when two oceanic plates pull apart, magma rises and new crust is formed
Divergent boundary
where two plates are moving apart, magma comes up to create new crust
faults
A fracture created in the Earth's crust when strained beyond its ability to remain a solid unit Can displace rocks up or down, while others involve sideway movements Movement can be slow, but usually a sudden slippage occurs
More-or-less circular coral reefs enclosing a lagoon that no land inside it
Atolls
Slide #15-Transportation
Dissolved Load Minerals are dissolved in the water and carried in solution. The San Juan and Little Colorado River enter the Colorado River near the Utah/Arizona border and add a lot of dissolved salts to the Colorado River. Suspended Load Very fine particles of clay and silt are carried in suspension, moving along with the water without ever touching the streambed. The suspended particles have a very slow settling speed, even in still water. Most of the material carried by a stream is found in the suspended load. The Mississippi River carries 90% of its load in suspension. The Mississippi River is called the "big muddy" because of its appearance. The Huang He in Northern China (Yellow River) looks yellow because it carries most of its load in suspension. The Yellow River carries more than a million tons of load in suspension every year. A stream during low water discharge will look clear. When the stream starts flooding the stream will look muddy and dark. Sand and gravel will get into the suspended load during a flood. Humid regions experience considerable weathering which produces many fine grain sediments. Bedload Sand, gravel, and larger rock fragments are carried in the bedload. The smaller particles are moved along with the general streamflow in a series of jumps and bounces (saltation). The debris is transported some distance, dropped, then picked up and carried farther. Bigger pieces are moved along by rolling or sliding along the streambed (traction). This is like a bulldozer pushing dirt. Traction movements are usually very brief. Many times an object will stop rolling or sliding when it gets stuck against another object. Streams dominated by the bed load tend to occur in arid regions because of the limited weathering rates in arid climates. Limited weathering leaves considerable course grained sediment in the landscape. These course grained particles are too large to be carried by the suspended load. During a time of low flow, part of the suspended load becomes the bedload.
Slide #10-Canadian Shield
During the ice age a glacier stripped dirt off the Canadian Shield and deposited that soil in the Upper Midwestern United States. The Canadian Shield is nothing but bare rock, lakes, and a few pine trees. It is almost completely unpopulated with the exception of the occasional small mining town. Glaciers have influenced the slope and drainage of the Midwest. Glaciers are responsible for almost all lakes in the upper Midwest and Canada. Glaciers are also partially responsible for the very flat topography of the Midwest.
Slide #7-Drought in the Western U.S.
Hoover Dam is 143 feet lower in the picture taken in 2009. Average annual precipitation in the region has only been 70-75% of the normal amount. The extent of the decrease is visible on the bleached canyon walls on the edge of the lakes. Marinas that were built on the Colorado River are now a quarter to a half mile away from the river because the water has dropped so dramatically.
An uplifted piece of land in the Basin-and- Range region of the United States
Horst
What is meant by magnitude?
How strong an earthquake is
Slide #14- Mount Rainier
If Mt. Rainier erupted, the eruption would cause ancient glaciers on the mountain summit to melt. This would cause a massive flood of volcanic debris and water that would sweep down into populated areas causing numerous deaths and massive property losses.
Slide #7-Volcanic Distribution
Most volcanoes occur along oceanic/continental convergent tectonic plate boundaries and along oceanic/oceanic convergent tectonic plate boundaries. Some volcanoes also occur along divergent tectonic plate boundaries and hotspots
Mt. Vesuvius in Italy
Mount Vesuvius erupted in AD 70 killing over 20,000 people 5-6 inches of volcanic debris on the city of Pompeii which was six miles away Mt. Vesuvius has erupted 18 times in the last two thousand years and last erupted in 1944
The massive super continent is called
Pangea
East African Rift Valley
The East African Rift Valley is located on a divergent boundary The East Africa Rift Valley is bordered by steep cliffs exposing rocks that are two million years old The Red Sea is the result of spreading taking place within a continent
Slide #27-The Formation of the Himalayan Mountains
The Himalayas began forming 35 million years ago, when the subcontinent of India started colliding with Asia. India moves half an inch towards the northeast every year. It keeps pushing farther and farther into Asia. It is like soil being scraped up by a bulldozer. The Himalayan Mountains have the ten highest peaks in the world. The crust under the Himalayas is 43 miles thick, which is double what is under North America. The collision of the Arabian and Eurasian tectonic plates has created numerous mountain ranges in the Middle East. Middle Eastern countries are noted for frequent earthquakes. The area around the Himalayan Mountains also has a lot of earthquakes.
Slide #8-Desert Landscapes
The mountain ranges of the Desert Southwest are long and narrow. The mountain ranges (horst) are caused by normal faults and are parallel to one another. This inhibited settlers on their journeys west. With the combination of desert climates and north-south facing mountain ranges, many people perished.
Slide #17-Cinder Cone Volcanoes
They are usually only 1,500 feet high. They are like a mini version of a composite volcano. Most cinder cones are produced by a single, short lived eruptive event. Half of the cinder cones are constructed in less than a month and 95% are constructed in a year. The lava in magma chamber of the volcano becomes solidified, so the volcano becomes extinct rather quickly. Cinder Cones also erode quickly because they are formed of unconsolidated materials.
Great African Rift
This place is in Africa and the plates are coming apart.
A ______ detects the magnitude of an earthquake
a seismograph
convection currents
circular movement of a substance due to changes in temperature and density
Slide #30-San Andreas Fault Movement
28,000 buildings were destroyed in the 1906 San Francisco Earthquake. Many of the survivors moved to Oakland and other East Bay towns. Roughly 2,500 people died in the 1906 San Francisco Earthquake. Most people were killed by fires. Experts believe that there should be an earthquake on the southern portion of the San Andreas Fault every 150 years. In the 1857 Fort Tejon quake, a portion of the San Andreas Fault from San Bernardino to the Central Valley slipped. The epicenter of the 1857 Fort Tejon Earthquakes epicenter was near Wrightwood California. Wrightwood is in the San Gabriel Mountains near the ski resort "Mountain High". Only one person was killed by the 1857 Fort Tejon earthquake, but shaking was felt as far away as Las Vegas and San Diego. Experts believe it was a magnitude 8 earthquake. Tulare Lake which is over 60 miles away from the epicenter of the Fort Tejon Earthquake had fish that were thrown far out of the lake by waves that were generated by the earthquake. The picture on the slide is of the 14 freeway in Palmdale, California. The San Andreas Fault is visible in the picture.
the desert southwest
30 million people depend on the Colorado River Arizona's population doubled between 1990 and 2007 reaching 6.2 million Phoenix had 200,000 people in 1953 and now it has 4.3 million Las Vegas had 368,000 people in 1985 and now it has 2 million
Damage and Predictions
A 7.0 magnitude earthquake hit Haiti in 2010 and killed over 300,000 people In 2010 a magnitude 8.8 earthquake hit Chile killing 521 people Electronic waves move faster than earthquake waves and this makes it possible to issue warnings
composite volcano
A Composite Volcano is a large, steep sided, symmetrical cone They violently erupt because the high viscosity lava does not let the pressure escape A Composite Volcanoes is composed of many layers of lava and pyroclastic materials
Slide #18-Alfred Wegener
A few scientists in the southern hemisphere believed Wegner's hypothesis because that's where the best evidence of continental drift is located. In 1930, Wegner was leading a meteorological expedition on the ice cap of Greenland. He was trying to set up a weather station to support commercial flights between Europe and the United States. Wegner and his assistant were moving supplies by dog sled to the weather station that was going to be staffed by a weather observer all winter long. After the last planned trip, the weather observer decided that he needed more supplies and threatened to leave if they did not return with more. Both Wegener and his assistant were reluctant to go get more supplies because winter was fast approaching but did it anyway. Wegner and his assistant set out by skis and dogsled to return to their basecamp near the coast. Neither arrived and Wegener's body was discovered the next summer by a search party. Wegner's assistant's body has never been found.
Slide #9-Playa & Alluvial Fan
A playa (which is Spanish for beach or shore) is the valley (graben) floor. Silt and sand accumulates to remarkable depths on the playa floor. The playa rises at the expense of the mountains. Wind blowing over the playa moves the shallow water along and this helps fill the low spots in the playa. Playas are the flattest landform on earth. Most streams find their way to progressively larger streams and eventually into the ocean. In some regions of the desert the streams do not reach the ocean. Instead water enters a playa and is evaporated or seeps into the soil. The Humboldt River flows 290 miles across Nevada and evaporation and seepage causes it to disappear into a large playa. Rainwater runoff in the deserts is typically very salty because it flows over salt rich mineral deposits. When the water flows into the playa it evaporates into the dry desert air, but the salt remains. Salt flats are encrusted with salt deposits. Companies will mine these areas for potassium and sodium. Edwards Air force Base is on a playa and has served as a landing site for the space shuttles and military aircraft. It gets flooded some times and is closed. The Bonneville Salt Flats in Utah (where the land speed record was set) usually has 1-2 inches of water on it during winter. Alluvial Fans Alluvial fans occur at the mouth of a canyon where it exits into a valley. The flowing water abruptly loses velocity as it leaves the restricted channel of the canyon. Fan formation is rare in humid climates because streams that flow year-round will carry away sediment. The lower part of the stream channel sweeps back and forth below the apex of the alluvial fan. This accounts for the semicircular nature of the alluvial fan below from the apex. The alluvial fan produces a stream channel pattern that sometimes shifts from channel to channel. A logical aspect to the alluvial fan is sorting of minerals by sizes. Near the mouth of the canyon you have larger minerals and they slowly get reduced to finer particles the farther away you get from the mouth of the canyon. Some alluvial fans can be many miles across. The running water can cut channels into the fan, but frequently new alluvium deposits build atop the old. A continuous apron or "bajada" may form if individual fans coalesce into one sloping surface.
Slide #33-Accreted Terranes
A terrane is a small-to-medium island that may have been carried a long distance by a drifting plate that eventually converges with another plate. The island is too buoyant to be subducted in the collision and is fused (accreted) together to the other plate, often being fragmented in the process. Terranes are distinctive geologically from the rest of the coast because they have different rocks from the plate they fuse to. Every continent has grown outward by the accumulation of accreted terranes on one or more of its coasts. The coast off Northern California, Oregon, Washington, British Colombia, and Alaska consist of a mosaic of several dozen accreted terranes. Some of the rocks origins have been traced from south of the Equator. India is an example of an accreted terrane. The Galapagos Islands are on a crash course with western South America and will eventually accrete to South America.
Slide #8- Volcanoes in the U.S.
At Lassen Peak volcanic activity started in May each year. Geologists think that water from the melting snow sank into the ground and was heated underground by the magma. The steam created by the geothermally heated water helped fracture Lassen Peak. The fractured surface of Lassen Peak reduced internal pressure and the eruption would begin. To this day Lassen Peak still produces gas and steam. It has the potential to erupt. Mount Shasta (pictured on the slide) is 10,000 feet higher than its surroundings and can be seen from easily 140 miles away. Mount Shasta erupts every 250 years and last erupted in 1786. There is a religion called "I am" which was funded in the 1930s. The religion says that a group called the "Lemurians" (who were from a lost continent) established a secret city in the mountain. Very few members of the religion live near the mountain, but pilgrimages and festivals occur during the summer and swell the population of nearby towns.
Slide #17-Wash
A wash is called an "Arroyo" in Spanish. Streams in arid environments typically carry a greater concentration of sediment load (in comparison to water discharge) than streams that are a similar size in humid areas. There is insufficient vegetation in the desert to break up the force of the raindrop. The lack of extensive root networks makes the rock fragments very easy to move. The soil is also called "desert pavement" and is often very impermeable. When the rain falls the water starts almost immediately collecting in streams. Rocks are pushed into the main channel producing debris flows. These streams have a short lag time of only an hour or two, so when there is intense rainfall the streams quickly rises to a high level. The weather bureau usually does not have a lot of time to issue a flash flood warning. People seem to not take flood warnings seriously too often anyway. Novices to desert camping will pitch their tents in a wash because they find soft, flat sand to sleep on and shelter from the winds. Many people every year die in a vehicle that was stalled in rising water. Cars begin to float when the water around the vehicle is over two feet. Once the cars starts to float just a little, the moving water often carries it into deeper waters or often times overturns it. Fresh water moving at 4 mph exerts force of about 66 pounds on each square foot it encounters. When you speed it up to 8 mph the force is 264 pounds per square foot. They don't recommend wading across a flooded area unless you can see the bottom. In August of 2004, several thunderstorms cells stalled over the mountains along the east side of Death Valley. Rainfall reached 2.5 inches in less than an hour (Death Valley usually gets less than 2 inches a year). Cars were swept away in the Furnace Creek parking lot. Two people were killed. The rushing water got as high as 10 feet in some places.
Divergent Boundaries
Are constructive because material is being added to the crustal surface A continuous line of volcanoes (Midoceanic Ridge) spills lava out onto the ocean floor Heat weakened rocks are less rigid and do not build up and store huge stresses necessary to create large earthquakes
Flash Floods in Las Vegas
As much as 80% of the urban surface is not permeable Rain cannot seep into the cement, so it quickly becomes runoff Storm drains carry the runoff from paved areas to stream channels, which quickly increases the amount of water the stream is carrying
Slide #24-Convergent Boundaries
At a convergent boundary the tectonic plates collide with each other. These are called "destructive" boundaries because they result in the removal or compression of the surface crust. Convergent boundaries are responsible for some of the most massive and spectacular of earthly landforms: major mountain ranges, volcanoes, and deep oceanic trenches. Oceanic/Continental Tectonic Plate Convergence Where ever a continental-oceanic tectonic plate convergent boundary exists a mountain range is formed on land. The Andes Mountains on the West Coast of South America parallels a deep oceanic trench. The Andes Mountains are the second tallest mountain range in the world. Earthquakes take place along the margin of the subducting plate. Volcanoes develop from the magma generated at the subduction zone. Many of these volcanoes frequently erupt explosively. The Andes Mountains on the West Coast of South America are known for volcanoes, large earthquakes, and tsunamis. The Cascade Mountains in Oregon and Washington are created by the Juan de Fuca tectonic plate subducting down below the North American tectonic plate which is called the Cascadia Subduction Zone. The Cascades are a volcanic mountain range. A major earthquake is supposed to occur every 500 years at the Cascadia Subduction zone. The last one was in 1700. The Cascadia Subduction zone is capable of producing a magnitude 9 earthquake with an accompanying tsunami. The set up is very similar to the Andes Mountains. Portland and Seattle have strict building codes to try to prevent against earthquake damage.
Slide #36-Liquefaction
Bedrock In many areas bedrock lies near or at the earth's surface and buildings are anchored to the rock. Bedrock vibrates during an earthquake and the building may collapse if it is violent enough. However, bedrock returns to its original shape when the earthquake is over. If the building withstands the quake, it will survive .Building on bedrock is very desirable in earthquake prone areas. Sand and Gravel Loose unstable soils like sand, silt, and clay soils settle during earthquakes and this displacement tilts buildings, breaks pipelines and roadways, and fractures dams. These soils tend to amplify the ground shaking. Building on soft ground will shake much more strongly than those located on bedrock. Bad places to build on include stream valleys that were covered with loose materials. Shaking from an earthquake on loose soils can be five times greater than the level of shaking on bedrock. To avert structural failure in such soils, engineers drive down steel or concrete pilings through the sand and attach it to the bedrock below. These pilings anchor and support the structures even though the ground below them settles. Soft Mud Loose, water-saturated sediments like coastal landfill may undergo liquefaction. The water-saturated material will turn to fluid because the grains of sediment will move closer together expelling the water. The shaking turns solid ground into a molasses like mix. This results in subsidence and fracturing. Since 1900, about half the original surface area of the San Francisco Bay has been reclaimed with landfill. Much of it was debris from the 1906 earthquake. Also miners used hydraulic mining (high powered hoses that wash rock debris downstream) during the Gold Rush and a lot of that loose sediment settled in the San Francisco Bay. This landfill created over 200 acres of lowland. Much of the Marina District in San Francisco is built on landfill. Many buildings in the Marina District were destroyed in the Loma Prieta quake. The Marina district is on the north side of the city near the parks and Golden Gate Bridge. Ground motion in the Marina district was 10 times stronger than nearby sites on bedrock. The Cypress Structure on Interstate 80 (pictured on the previous slide) was built on soft sediment and 1 ¼ mile section collapsed killing many drivers. Most of the rest of Interstate 80 was fine. To avoid this happening in the future San Francisco needs to install drains and pilings that are put in fill areas. This will cost several hundred billion dollars. The San Francisco's new airport terminal is a 115 million pound building resting on 267 stainless steel sliders that sit in big concave dishes. The terminal can roll 20 inches in any direction. In 1995, a 6.9 magnitude earthquake rocked Japan exactly one year to the day from the Northridge quake. Areas in the Osaka Bay reclaimed by landfill taken from the sea liquefied quickly in the shaking.
Slide #18-Big Thompson Canyon
Big Thompson Canyon is about 50 miles northwest of Denver. The flood happened in July of 1976. By 6pm thunderstorms started appearing above the Rockies and instead of drifting eastward they stayed in place. Big Thompson Canyon's steep rocky slopes absorbed little of the rain. The river moved fast enough to move 10 foot boulders. Many people had very little idea what was happening because the sun had been shining all day in the canyon. A similar event happened in the Black Hills of South Dakota in 1972 and the flood there killed 237 people. Most of Big Thompson Canyon has been rebuilt. Signs in the area read "Climb to Safety in Case of a Flash Flood". People should always try to get to higher ground in a canyon flash flood situation. You are better off being cold and wet on a hillside watching your car being smashed against the rocks than being in it.
Explosive eruptions may cause the volcano to collapse into the floor of the empty magma chamber producing a large depression
Caldera
Slide #20-Calderas
Calderas are uncommon in nature. It is produced when a volcano explodes and then collapses. The result is an immense basin-shaped depression, which is generally circular. The depression has a diameter that is many times larger than that of the original volcanic crater.
Slide #14-Capacity
Capacity also depends on the characteristics of the load, particularly the mix of large and fine sediments. 50 million gallons of Amazon water is deposited into the Atlantic Ocean every second. A lot of the water being discharged into the Atlantic is still freshwater. Deposition at the mouth of the Amazon River has formed islands offshore. The Yellow River in China is half sediment, half water.
Slide #14-Continental Drift
Continents have moved, collided, merged, and been torn apart again. Ocean basins have formed, widened, and eventually were closed off again. The current configuration of the continents and oceans is by no means the ultimate one. In the early 1900s, most scientists believed that the continents and oceans were in a fixed position and only by changes in sea level and mountain building were they modified. Scientists believed that the present arrangement of the continents and oceans took shape because of how earth's crust cooled from its molten state early in the planet's history. Scientists recognized that the earth had a hot interior and it was losing heat through the surface. They believed that the earth was cooling and contracting and mountain ranges were like wrinkles on a drying apple. They said that the collapse of some sections of the earth's surface was responsible for the ocean basins. Alfred Wegner was a German meteorologist and geophysicist. He published the book "Origin of Continents and Oceans" which was written is German.
Slide #21-Crater Lake, Oregon
Crater Lake is located in southern Oregon, northeast of Medford. A composite volcano that was 12,000 feet tall exploded 7,700 years ago. During an eruption the magma chamber was emptied. Once the magma ceased to flow to the top of this volcano, the walls of the mountain weakened because they were no longer supported by the upflowing magma. Crater Lake is 2,000 feet deep and six miles across. It is the deepest lake in the United States and the 7th deepest in the world. A volcanic cone has built up from the bottom of the lake and now breaks the surface as an island. It is called Wizard Island.
Slide #10-Death Valley
Death Valley is 140 miles long and 4-16 miles wide. The low spot is -282 feet below sea level. Tilted fault block mountains border each side of Death Valley which is a graben. There is a high point called Telescope point on the western mountain ranges that is 11,049 feet. Telescope Peak is only 18 miles from the low point.
Alfred wegener
Despite the evidence, most scientists in the 1920s did not accept continental drift Wegener never developed a solid theory for why and how the continents were able to move It wasn't until Wegener died that the scientific community finally embraced continental drift
What are negative impacts of a volcano?
Destroys animal habitats, ash cloud disrupts flights, people have to be evacuated
Slide #10-Volcanic Ash and Air Travel
During the last 15 years 80 commercial jets have been damaged by flying into a cloud of volcanic ash. Because ash clouds are dry, they don't appear on weather radar. Weather radar only measures the moisture in a cloud. A British Airways flight in 1982 encountered an erupting volcano over Indonesia. All four engines failed when the plane entered the ash cloud. The flight lost 25,000 feet in elevation before three of the engines were restarted. The Guinness Book of World Records recorded it as the longest glide ever from a non-glider aircraft. The plane almost crashed into the ocean. In 1989, a Boeing 747 encountered an ash cloud above Alaska. All four engines stalled because they got so clogged with ash. The engines were able to be restarted at the last minute and the plane was able to make an emergency landing. It fell for 14,000ft. 2010 Iceland Volcano Flights were canceled in Europe from April 15th to April 23rd 2010 in most of Europe due to concerns about the ash from a volcano in Iceland. It was the highest level of air travel disruption in Europe since World War 2. Air travel was canceled intermittently in different parts of Europe in the weeks that followed. What made the volcano so disruptive for air travel was a combination of three factors: 1. The volcano was directly underneath the Jet Stream. 2. The direction of the Jet Stream was unusually stable at the time of the eruption. It continually blew southeast. 3. The erupting lava cooled very fast which created a cloud of highly abrasive glass-rich ash.
Slide #3-Colorado River
Early explorers who visited the Grand Canyon said they were kept up at night by the thundering rapids of the Colorado River. Large pieces of rock material were moved by the Colorado River before the dams were built. The steep grade of the Colorado River was perfect for hydroelectric power. The Colorado River and its many tributaries flow across rocks that contain soluble salt deposits. The evaporation from the reservoirs has further concentrated the salty water. Irrigated water percolates through the soil and passes through thick mineral salt deposits on its way to rejoining the river. There are two rivers that flow into the Green River in Utah that are saltier than the ocean. When the Colorado River got to Mexico it contained 27,000 salt parts per million. Normal large rivers have 1,000 salt parts per million. The water was so salty by the time it got to Mexico that if you poured it on a plant it would kill it. Restaurants near the Colorado River used to serve water with a slice of lemon to try to mask the saltiness. The United States signed a water allocation agreement with Mexico in 1923. In the past, a person could dam the river upstream and the people down river were left with nothing but a bed of dry rocks. The purpose of the agreement was to sustainably allocate water in a fair and equitable manner by establishing a system of water rights. Northern Mexico is one of the country's most important agricultural areas and the water they were getting from the Colorado River was unusable. They started to complain about the situation. The United States responded that they were fulfilling their water agreement with Mexico because Mexico was getting the amount of water they were promised. We told Mexico that the salinity of the water in the Colorado River was their problem. In 1973, OPEC (Organization of Petroleum Exporting Countries) formed. Around the same time Mexico discovered large oil reserves off the Yucatan Peninsula. The United States agreed to remove the salt from Colorado River because we did not want to strain our relationship with Mexico amid a potential oil crisis. The desalinization plant built in Yuma, Arizona was 10 times larger than any in existence at the time.
Slide #13-The Interior of Earth
Earth still has interior heat because we are cooling from the "Big Bang." The Russians have drilled a hole that is 7.6 miles deep and the temperature was 356˚. Miners in South Africa have been down 2.2 miles extracting gold and the temperature was 134˚. Mars is a smaller planet and cooled much more rapidly than earth. Mars lost its internal heat much earlier in its history. If you shrunk the earth down to the size of an apple: The core of the earth is where the seeds of the apple are. The mantle of the earth is the edible fleshy part of the apple that you eat. The crust of earth is the skin of the apple. The proportions are actually pretty much correct. Asthenosphere The asthenosphere extends from 60-200 miles beneath the earth. It means "weak sphere" because the rocks lose their strength and are deformed by the heat. When you heat a steel bar it can easily be bent or reshaped, even if it does not actually melt. The lower mantle is below the asthenosphere and above the core. The rocks in the lower mantle are believed to be solid. The asthenosphere is like hot wax or road tar. The asthenosphere allows the rigid continents to move. Continental vs. Oceanic Crust Continental crust is much thicker, but less dense than the crust at the bottom of the ocean. The ocean floor crust is thinner, but much denser than the continental crust. The average ocean depth is 14,670 feet. That amount of water pressure at the bottom of the ocean compresses the ocean floor.
Wash (Desert Streambed)
Ephemeral Streams are streams that only carry water right after rains Large amounts of debris are swept into the stream channel and travels with the floodwaters producing debris flows In 1997, 11 hikers drowned while in a slot canyon in Utah and the storm was 25 miles away
Slide #31-The Erosion of Kauai
Exogenic agents (wind and water) wear the cone shaped volcano away and ultimately it becomes a low island. Continued attack by the elements can reduce the island to a coral covered platform. Kauai has been carved into a masterpiece of physical geography. Kauai has deep canyons, steep cliffs, and scenic waterfalls. Waimea Canyon on Kauai is often called the "Grand Canyon of the Pacific."
Slide #24-Faults
Faults are zones of weakness in the earth's crust. Freshly poured concrete is smooth and strong, but stress on the road from driving heavy equipment over it and the resulting strain causes a fracture. Pieces on either side of the fracture may move up, down, or horizontally. Faults penetrate miles into the Earth's crust. Faults can extend along the ground for a thousand miles or just be inches long. Many faults are deep enough in the Earth's crust that there is no evidence on the surface a fault even exists in that location. Usually only one part of the fault system moves during an earthquake. The 1906 San Francisco earthquake occurred along 250 miles of the San Andreas Fault. The San Andreas Fault is longer than 250 miles
Endogenic Processes
Forces move crustal material upward through volcanic and tectonic processes Tectonic-means "carpenter" or "builder" in Greek Endogenic Processes are energized by earth's internal heat and operate outside of any atmospheric influences
Shield Volcanoes
Shield Volcanoes are broad, low lying volcanoes that resemble the shield of a knight They are often located on hotspots like Hawaii Because they have low viscosity lava they tend to produce very mild eruptions with no pyroclastic flow
Slide #4-Geomorphology Geo= Earth Morphology= shape or form
Geologists and geographers study a lot of the same things. Geologists focus a lot on minerals, rocks, geologic time, and the interior of the earth. Geographers mostly just study the shape of the earth's crust. Geographers seek to understand the evolution of mountains, the development of plateaus, and the process of shaping sand dunes, caves, and canyons. The topographic relief of the earth's surface is temporary. It represents the momentary balance of two largely opposing sets of processes (endogenic and exogenic) that are operating to shape and reshape the surface of the Earth. Endogenic Processes increase the relief of earth's surface. Exogenic Processes decrease the relief of earth's surface. Craters on the moon last forever. The Moon has no volcanism or earthquakes (endogenic forces) because it does not have internal heat. The moon has no atmosphere so there is no water or storms (exogenic forces). The surface of the earth is ever changing. The surface of the moon mostly stays unchanged.
Slide #6-The Desert Southwest
Global climate change may increase the frequency and severity of the droughts. The subtropical High dominates the weather of the American southwest and it is predicted to intensify and shift farther northward which would increase the extent of arid conditions. Warming temperatures will cause more evapotranspiration. There is a 50% chance that Lake Meade may be fully depleted by 2021. Lake Meade was only 35% full in 2005. 66% of the electricity generated by Hoover dam goes to Southern California. There may not be enough water to turn the turbines by 2017. The picture on the slide is of the 1831 London Bridge in Havasu City, Arizona. The bridge used to span the Thames River in England but was torn down in 1962 and sold to a land developer in Arizona.
Slide #12-Heimaey Island
Heimaey Island is located on the southern coast of Iceland. Fishing is responsible for 80% of Iceland's foreign exchange. Heimaey Island lands and processes 20% of Iceland's fish catch. The Eldfell Volcano erupted in January of 1973 and was active for four months. It would have destroyed the village and harbor if action was not taken. The government of Iceland used sea water to cool down the lava and help redirect the flow. The new land created by the volcano actually made the harbor more effective because it sheltered the boats better. All the residents were safely evacuated by boat and airplane. About 80% of the population returned to the island right after the volcano became inactive. Lava flows and ash did destroy some people's homes and they were unable to return. Only one person died due to the volcano. A man stayed on the island after the evacuation and was looting pharmacies of prescription drugs. He died due to suffocation from the volcanic ash. A square mile of land was added to the island by the volcano (endogenic processes). Now wave action and running water (exogenic processes) are slowly wearing down the new land that the volcano added to the island.
Slide #22-Divergent Boundaries
Iceland is pictured on the slide. The Mid-Atlantic ridge rises above the surface in Iceland. Iceland is growing because it is slowly spreading apart 2 centimeters per year. You can see the divergent boundary in the image on the slide. The North American Plate is on the left side of the crack and the Eurasian Plate is on the right side of the crack. Midoceanic ridges produce shallow-focus earthquakes. The focus of an earthquake at a divergent boundary is usually shallower than 45 miles in depth. Iceland gets earthquakes frequently, but they are rarely large earthquakes. Iceland also has a lot of volcanoes and geothermal activity (like geysers and hot springs) because it is located on a divergent boundary.
Los Angeles Aqueduct
In 1848 , L.A. relied on ground water and the L.A. River because the city had 1,600 people 250 miles away, the Owens River flowed out of the Sierra Nevada at 4,000 feet in elevation Los Angeles officials posed as real estate investors and bought up huge tracts of land
Krakatau Volcano
In 1883, a volcano on a small island in Indonesia erupted so violently that the island disappeared The explosion was heard over 1,864 miles away which is equivalent to the distance between Chicago and Los Angeles It generated a 115 foot tsunami that drowned 36,000 people
Mono Lake
In 1941, the Los Angeles aqueduct starting diverting water from 4 of the 6 rivers that flow into Mono Lake The lake has shrunk to half its original size and doubled in salinity In 1994, a ruling forced Los Angeles to allow more water to flow into Mono Lake
Paricutin Volcano
In 1943, a small hole existed in a flat area in a cornfield near Mexico City A Cinder Cone volcano grew to a height of 130 feet in one day The volcano grew to 1,400 feet a couple months later and produced lava flows that destroyed a small town
Slide #21-Los Angeles Aqueduct
In the early 1800s, Los Angeles was too far from the gold fields of Northern California to attract the miners or their money. It sat in the dry coastal basin without a good natural port or a railroad. Many early settlers in Los Angeles were Mormons that had become experts in irrigating dry farmlands. By the late 1800s, irrigated farms in the Los Angeles basin were producing a wealth of fruits and vegetables. Los Angeles has good sun, soil, and climate for growing agriculture, it just needed water. The slopes of the Western Sierras have numerous rivers running to the Pacific. The eastern side of the Sierra Nevada has very few rivers and the ones that do exist are generally small. The Owens River was the one exception. Because the Owens River was at 4,000 feet in elevation the water could be carried in pressure aqueducts and siphons under the force of gravity. The Kern and Colorado River require thousands of feet of lifting to get the water to Southern California. This was impossible at the time and way too expensive for Los Angeles County even if it was possible.
Slide #4-Sediment Accumulation
Lake Mead lost 6% of its capacity in the first 35 years of its existence due to sediment accumulation. At this rate Lake Meade may only last 100 years. Lake Powell is also forecast to fill with sediment by the end of this century The damns greatly reduce the sediment flowing down river. Dams act as sediment traps. Reservoirs will eventually fill with sediment because the current slows. Reservoirs fill at 1% annually on average. The disturbed pattern of seasonal flow has formed sandbars and water demanding plants have rooted themselves on these sandbars sucking up more water. The plants transpire water into the hot air. Lake Meade is periodically flooded by the USGS to try to push the accumulated sediment farther downstream.
lava flows
Lava flows rarely cause a loss of life, but can cause significant property damage Paths taken by lava tends to be very predictable and causes few injuries Some lava flows move at 15 miles per hour and can travel 75 miles before stopping
lava dome
Llava bulges up from the vent and the dome grows largely by expansion from within Lava Domes are usually less than 2,000 feet high and have a very irregular shape Lava domes usually produce very violent eruptions
Slide #22-Long Valley Caldera
Long Valley is one of earth's largest calderas. It is 20 miles long, 11 miles wide and 3,000 feet deep. A caldera is a giant bowl shaped depression that was formed when the magma chamber collapsed after a large eruption. The causes of the Long Valley Caldera volcanism are still largely unexplained. Long Valley is not above a Hotspot like Hawaii or Yellowstone. It is also not the result of subduction which is what produced volcanism in the Cascade Mountains. The Inyo Craters in the Long Valley Caldera were active less than a thousand years ago. Future eruptions in the Inyo Craters are very much expected. The Inyo Craters are actually lava dome volcanoes, not craters. Mammoth Mountain In 1980, four earthquakes that measured 6 on the Richter scale rocked Mammoth Mountain. Swarms of small earthquakes continued until 1982. The magma below the ground also got a foot closer to the surface. On May 27th 1982, Federal Geologists issued a notice of a potential volcanic hazard at Mammoth. Housing prices fell by 40% overnight. In the next couple years dozens of businesses closed, new shopping centers stood empty, and people left the region to seek jobs elsewhere. The swarm of earthquakes continued to rattle nerves in the area until mid 1983. The economy of the Mammoth area did not recover until 1986. The area will still get swarms of earthquakes every so often, but the USGS is very reluctant to issue any type of potential volcano warning.
Slide #15-Origin of Continents and Oceans
Maps were drawn by hand during this time and people commented on the complimentary shapes of the coastline of Eastern South America and Western Africa, but the matching patterns were considered little more than a coincidence. If you look on a map, Madagascar also fits very well into the southeastern coast of Africa. There are other examples of coastlines fitting together throughout the world. Large coal deposits which stretch from North America to Europe to China existed because these regions were once more equatorial in location and therefore were covered with lush tropical vegetation which eventually became coal.
Slide #31-Map of Major Faults
Mendocino Fracture Zone has some notable earthquakes. The Mendocino Fracture Zone is the location where the San Andreas Fault connects with the Juan de Fuca tectonic plate. In July of 1991, 4 earthquakes ranging in size from 6.3-7.1 magnitude occurred along this area. An 1872 earthquake on the Owens Valley Fault (not pictured on map) killed 10% of the people in the town of Lone Pine. This occurred before seismometers were developed and it may have been California's most sizable recent earthquake. If this happened today it would greatly affect communities like Lake Tahoe and Reno. The Hayward fault has a 28% chance of producing a 7.0 earthquake in the next 10 years. The San Jacinto fault is capable of creating a 7.5 magnitude earthquake. Earthquakes are somewhat common in Southern Mexico and Central America because the Cocos Tectonic Plate is subducting beneath the North American and Caribbean Tectonic Plates.
Slide #37-1985 Mexico City Earthquake
Mexico City is built on an ancient lake bed made of clay rich sediment. The city is surrounded by mountains. The epicenter was 240 miles away in Acapulco City and there was comparably little damage there because the Acapulco City is built on bedrock. The earthquake waves shook the wet clay beneath Mexico City back and forth between the mountains like waves in a bowl of Jello. High-rise buildings in Mexico City completely collapsed.
plateaus
Mexico City is the largest city in the world. It is located in a plateau. Mexico City is located in a fairly flat area, but is a mile and half above sea level. Some plateaus are densely settled and some are not. Plateaus in East Africa get lots of rainfall and are densely populated by farmers. The Tibetan Plateau is a high, dry area that is thinly populated by nomadic herders.
Slide #34-Seismographs
Modified Mercalli Scale (uses Roman Numerals) was developed to compare different earthquakes. This is useful in evaluating damage from earthquakes in the past when there was no seismographs. Modified Mercalli Scale was like the Fujita scale and just measured the damage. An earthquake near the epicenter was X and 100 miles away it was Y. If there was a large city there was a greater chance of buildings being damaged, than compared to a rural area. Also building construction played a big role in the amount of damage. It was a flawed rating system. Richter Scale The Richter scale was developed by Charles Richter in 1935. It was the first earthquake scale to use seismographs rather than subjective estimates. Also it compensated for the distance between the seismograph and the focus. This means that each seismic station will calculate the same magnitude for a given earthquake, no matter how far away the epicenter was. There are over 4,000 seismographs worldwide. Richter scale magnitude is calculated on a logarithmic scale. A magnitude 4 earthquake releases 32 times more energy than a magnitude 3. A magnitude 5 earthquake releases 1 thousand times more energy than a magnitude 3. A magnitude 7 earthquake releases 1 million times more energy than a magnitude 3. Every year many thousands of earthquakes occur around the world. Most are located in remote areas. Only 80 to 100 are large enough to cause damage or the loss of life (magnitude 6 or higher). About a 15-20 magnitude 7 earthquakes occur every year in the world. A magnitude 8 earthquake occurs once every couple years. All the magnitude 9 earthquakes occurred along a convergent plate boundary and along the coastline of the Pacific Ocean. 75% of earthquake activity is released along the boundaries of the Pacific Plate. The Chilean earthquake of 1960 was a 9.5 magnitude The Alaskan earthquake of 1964 was a 9.2 magnitude The Sumatran earthquake of 2004 was a 9.1 magnitude The Russian earthquake of 1952 was a 9.0 magnitude The Japanese earthquake of 2011 was a 9.0 magnitude Many geologists think that a magnitude 10 earthquake will never happen because no fault on earth is long enough to cause an earthquake that size. Alaska Earthquake The Alaska earthquake in 1964 lasted 3-4 minutes and killed 131 people. This earthquake occurred on Good Friday when many people had the day off from work and school. If schools and businesses were open, the death toll would have been much higher. It was also the offseason for fishing, so people were not at the docks or canneries. After the initial earthquake, 10 aftershocks that were magnitude 6 and higher occurred over a 24 hour period. This helped destroy already severely damaged structures.
Slide #24-Mono Lake
Mono Lake fell by 45 feet in the 1980s. Salinity doubled and the wind picked up the loose sediment. Mono Lake is a huge migratory stop for birds and ducks. They eat the shrimp in the lake and the insects around it. The Gulls living around Mono Lake were in jeopardy because the brine shrimp that they fed on were dying because of the high salinity. The islands that they nested on were now becoming part of the shoreline, making them vulnerable to predators.
Slide #32-Yellowstone Hotspot
Most hotspots occur in the ocean, but a few occur on land. The Yellowstone hotspot is an example of a hotspot occurring on land. The hotspot has moved over time reflecting the western migration of the North American Plate. The Yellowstone Hotspot has had 3 major eruptions in the last two million years. About 16 million years ago the hotspot was located in Southeastern Oregon. Between 12 million years ago it migrated across southern Idaho. It has been in Northwestern Wyoming for the last 2 million years
Slide #11-Lava Flows
Most lava flows move slower than the average person's walking speed. As lava flows cool and begin to congeal, the lava's mobility decreases and eventually the lava flow stops. Dozens of homes have been destroyed by the lava flows from the Kilauea Volcano on the Big Island of Hawaii.
Slide #23-Volcanoes and Climate
Mount Pinatubo caused an ash cloud that rose 22 miles into the air. Mount Pinatubo had not erupted for 500 years. The "year without a summer" had heavy snow in June, frost in July and August, and very low winter temperatures. This eruption caused 3 days of complete darkness in Australia. Food riots broke out in England and France and food warehouses were looted. The painting "The Scream" on the slide was inspired by the red tinted sunsets they were having in Europe in 1883 and 1884. The red tint was caused by the Krakatoa volcano that erupted in Indonesia. The Krakatoa Volcano dropped global temperatures by 2.2° for two years. In 1783, an eruption in Iceland released so much acidic gas that nearly 1/3 of the people and half of the livestock in Iceland died. Benjamin Franklin thought that volcanic ash from an Icelandic Volcano reduced solar insolation and was responsible for the unusually cold winter of 1783-84.
Slide #1-Mount St. Helens
Mount St. Helens is located in the Cascades. The Cascades are formed by the Juan de Fuca Tectonic Plate subducting below the North American Tectonic Plate. The Juan de Fuca Tectonic Plate is a small oceanic plate that subducts below the coastline of Oregon, Washington, and Northern California. The Juan de Fuca plate melts and the magma rises to the surface. This causes the Cascades to be a volcanic mountain range. Mt. St. Helens erupts every 100 to 200 years. It had last erupted in 1857. Just two years before St. Helens erupted the USGS characterized it as the most active and explosive volcano in the lower 48. They virtually guaranteed it would erupt by the year 2000. Between 1975 and 1980 there had been 44 recorded earthquakes near the volcano. Before the eruption 50-100 small earthquakes were being recorded a day, so the locals really started to take notice. Small earthquakes (called harmonic tremors) signal that the magma chamber is filling up. Harmonic tremors are slow, steady vibrations, unlike the sharp release of energy associated with a normal earthquake. The volcano increased in size horizontally and vertically. A portion of Mount St. Helens started growing at 6 ½ feet per day before the eruption. This area grew 500 feet from its original elevation. This caused concerns about the mountain getting too steep and causing a landslide. A massive bulge began on the north side of Mount St. Helens. This indicated to geologists that that a lateral blast was very likely. Two months prior to St. Helens eruption the government had evacuated people from a 15 mile radius. People were very upset and disobeyed the orders. Some people even climbed up to the summit during this time. Tourists started flocking to the area. A group of loggers disobeyed the evacuation warnings on the day of the eruption and died. Despite the sophisticated array of instruments and the team of experts studying the mountain, there had been no clear signal that the mountain would erupt that day. There was no rise in earthquake frequency, no change in gas emission, and no sudden increase in the size of the bulge. Mount. St. Helens erupted at 8:32am. A famous volcanologist radioed "Vancouver, this is it" before he was cut off and killed by the blast. Mount St. Helens killed 62 people who had chosen not to evacuate.
Slide #4-Mount Vesuvius in Italy
Mount Vesuvius is the only volcano on the European mainland to have erupted in the last 100 years. Mount Vesuvius is 6 miles east of Naples, Italy. If Vesuvius erupted again it could impact 3 million people. The remains of the victims in Pompeii were quickly buried in the falling ash which the rain cemented before the bodies had time to decay. Many people suffocated because of the thick ash. Vesuvius erupted in 1944 and damaged 88 U.S. military aircraft that were at an Air force base nearby.
stream erosion
Moving water excavates and transports material at the bottom and the sides of the stream The flow speed is determined by the slope angle and the volume The turbulence of the stream is determined by the flow speed and by the roughness of the stream channel
Slide #13-Mudflows
Mudflows can travel at 50mph and travel for 30 miles before stopping. A volcanic mudflow that traveled for 30 miles inundated a town in Columbia killing 20,000 people in 1985. An hour occurred between the eruption and the arrival of the mudflow. The mudflow was 16 feet deep. When Mt. St. Helens erupted, water levels in nearby rivers were 13 feet above flood stage. This destroyed many homes in the nearby area. Volcanic ash and water from melted snow formed huge mudflows that chocked streams, buried valleys, and engulfed everything in its path A typhoon hit the Philippines right after Mount Pinatubo erupted. The heavy rainfall from the Typhoon created a loose, unstable mudflow that slid downhill for months, burying towns, wiping out bridges, and ultimately causing more damage than the eruption itself. Geologists were able to predict the nature and general timing of the eruption of Mount Pinatubo which allowed 60,000 people to evacuate.
Slide #25-Normal Faults
Normal Faults result from the tension stresses pulling apart the crust. The crust on one side of the normal fault is raised relative to the other. This creates a steep, straight cliff like feature called a fault scarp or escarpment. Fault scarps range in heights and can be up to 200 miles long. In Taiwan, an earthquake in 1995 instantly created a fault scarp which destroyed a bridge and formed a new waterfall. A 1983 earthquake in Idaho created at 10 foot high fault scarp that several people witnessed. Most of the people were knocked off their feet.
Slide #37-Folding (Compression)
Our common experience is that rocks are hard and brittle. If subjected to stress, rocks would be expected to break, bending is harder to visualize. When great pressure is applied for long periods (particularly in an enclosed, heated, subterranean environment) the result is often a slow plastic deformation that can produce folded structures of incredible complexity. If the compressional forces act very slowly then the rocks are more likely to ben instead of break. A table cloth will bend and rumple into folds if you push the cloth from opposite ends. Folds in some rock layers are very small, covering only a few inches, while others are enormous with the vertical distance between the upfolds and downfolds measured in kilometers. Folds can be tight or broad, symmetrical or asymterical. Folds that are symmetrical (that is each limb has about the same dip angle) if they are formed by compressional forces that were relatively equal from both sides. If compressional were stronger from one side, a fold may be asymmetrical, which means a dip of one limb is much steeper that the others
Slide #12-Pyroclastic Flow
Pyroclastic materials are found 60 miles from the volcano. Tall eruption columns form over the volcano in an explosive event. Gravity overcomes the initial upward thrust and begins to fall. The pyroclastic flow can be 392˚ to 1,292˚. On the Caribbean island of Martinique in 1902 a massive pyroclastic flow slid down the volcano and destroyed the city of St. Pierre, killing 28,000 people in a matter of moments. The Martinique Volcano started to erupt and people were trying to flee the city. The governor used the military to stop people from fleeing the city of St. Pierre. The election was the next day and he was worried that if people left the biggest city on the island he may not get reelected. The pyroclastic flow even destroyed boats in the harbor. Only one person in the town of St. Pierre survived. He was a murderer who was locked in an underground prison cell. He was badly scarred by the pyroclastic flow, but survived. The French government actually decided to set him free after the volcano erupted. He joined the circus and toured the Caribbean as "Prisoner of St. Pierre". In 1995, a volcano on the Caribbean Island of Montserrat destroyed half the island with volcanic ash and pyroclastic flows. Many people that lived near the site of the volcano evacuated the island and never returned. The island had 10,000 people and 7,000 people left for England, the United States, or other islands in the Caribbean. Most of the structures on Montserrat were damaged beyond repair. The remaining people had to migrate to the northern part of island where the land is rocky and soils are less fertile making life difficult. Much of the island is not inhabitable because of the possibility of another large eruption. In 1993, volcanic bombs in a volcano in Japan were 20 feet long and weighed 200 tons. They were blown 2,000 feet from the vent during the volcanic eruption.
Slide #26 Reverse Faults
Reverse Faults result from compressional stresses pushing together the crust. Reverse Faults are often found along convergent boundaries. The fault plane along a reverse fault is inclined so that one side rides up over the other. The side that rises up over the other is eventually worn down by erosion and smoothed out over time. Reverse Faults are hidden beneath the ground. There are a few reverse faults in the San Fernando Valley and Los Angeles County. Many times you don't know that a Reverse Fault is in the area until an earthquake happens. The 1971 San Fernando Earthquake (6.6 magnitude), the 1987 Whittier Narrows Earthquake (6.1 magnitude), and the Northridge Earthquake (6.7 magnitude) were all located on reverse faults that geologists didn't even know existed. The Puente Hills Fault and San Joaquin fault in Orange County are reverse faults.
Slide #8-Exogenic (External) Processes
Running water erodes the mountains causing numerous ravines and canyons. Running water will sometimes deposit the sediment worn from the mountains in lower elevation areas like a flood plain. Running water will sometimes increase the elevation of flat areas at the expenses of the mountains. High mountains exist where endogenic processes have operated at a faster rate than exogenic processes. The tallest mountains in the world are usually the youngest because erosion wears down older mountain ranges. Most large mountain ranges are composed of resistant rock. The Grand Tetons are a very young mountain range and are composed of resistant rock.
Slide #19-Plate Tectonics
Scientists thought the ocean floor was completely flat. It was not until they laid undersea telephone cables that scientists started to realize that there were undersea mountain chains. Sailors used to determine the depth of the water by lowering a weighted line until it hit the bottom. It could take 8 to 10 hours to do this if the depth was thousands of feet. All scientists had were spotty depth measurements throughout the oceans. Acoustic instruments called "echo sounders" were developed to measure ocean depths. An echo sounder generates a pulse of sound and accurately measure the time it takes to bounce off the sea floor before returning to the instrument. Because scientists knew the speed of sound traveling through water they could measure the depth beneath the ship. This enabled scientists to come up with a map of the ocean floor. These ocean floor maps were very beneficial for submarines. 85% of the ocean floor has actually been mapped by satellite readings of the small bumps and dips in the ocean surface. Gravitational pull causes water above the mountains on the ocean floor to rise slightly. Gravitational pull causes water above the deep spots on the ocean floor to dip slightly. Ridges and Trenches A continuous undersea mountain range (40,000 miles) wraps around the globe like the stitching of a baseball. The mid-Atlantic segment of this undersea mountain range is especially striking because it matches the shape of the east coast of South America and the west coast of Africa. This mountain range is called the Midoceanic Ridge. Narrow and deep oceanic trenches occurred in many places, often times near the edges of landmasses. The Mariana Trench near Guam is 36,198 feet below sea level, the Puerto Rico Trench is 28,224 below sea level, and the Java Trench in the Indian Ocean is 23,376 below sea level. Scientists believed that the deepest areas of the ocean were very far from land. After they mapped the ocean floor they realized that the deepest portions of the oceans were right off the coasts of some continents. By the 1960s, scientists had constructed a network of seismographs that was able to pinpoint the location of every single earthquake in the world. When the earthquake locations were mapped, it was clear that earthquakes did not occur randomly. Most earthquakes occurred near the midoceanic ridge system or the deep oceanic trenches.
Slide #27-Strike-Slip Faults
Slide #27-Strike-Slip Faults Strike-Slip Faults do not produce cliffs, but can form rift valleys. In some portions of a fault zone, rocks slip past one and another at a continuous snail like pace. The movement occurs without violent earthquakes. In other segments the plates pass each other in a series of hops creating destructive earthquakes. Strike-Slip Faults do not produce tsunamis. San Andreas Fault is pictured on the slide. You can see the movement of the San Andreas Fault in the picture. The orchard is offset by the movement of the Pacific Plate. Turkey has a strike-slip fault very similar to the San Andreas and it has produced a few large earthquakes. An earthquake in Turkey in 1999 killed 17,000 people. The Dead Sea Fault created the Sea of Galilee and the Dead Sea. The Biblical Story about the walls of the city of Jericho collapsing might have been caused by an earthquake on the Dead Sea Fault.
Slide #5-Lava
Slide #5-Lava Maple syrup has a much higher viscosity than water. Heating the maple syrup makes it less viscous and more fluid. You might have heard the expression, "slower than molasses in January." Temperature affects the viscosity of a substance. Bright orange and yellow lava is very hot, dull red and brown indicate cooler lava. If magma has a low viscosity, the dissolved gas will escape relatively easily. The lava may bubble and fountain as the gas escapes (especially in the beginning of an eruption), but the volcano will not explode. If the magma has a high viscosity it is harder for the gas bubbles to escape. When it does finally escape it usually erupts explosively. Volcanoes alter the landscape regardless of how violent the eruption. Volcanic soils cover just 1% of the earth's surface, but support 10% of the world's population. Java is a heavily populated country and has nutrient rich soils because of all the volcanic activity. When ash is blasted out of a volcano, nutrients can be leached into the soil in months. Just as our blood carries nutrients that nourish our bodies, volcanoes do the same for the skin of the earth. Lava contains elements required for plant growth.
Slide #33-Foreshocks and Aftershocks
Sometimes what we think is the main earthquake is followed by a larger earthquake. Then the original earthquake is considered a foreshock. After you have an earthquake there is a 6-9% chance that a larger earthquake will occur in the next three days. There were 3 greater than 6.0 earthquakes two days before the big earthquake in Japan in 2011. One of the earthquakes was a 7.2 magnitude. Aftershock- An earthquake large enough to cause damage will probably produce several felt aftershocks within the first hour. The rate of aftershocks dies off quickly. An earthquake will be called an aftershock as long as the rate of earthquakes is higher than it was before the main earthquake. For big earthquakes, this might go on for years. 700 aftershocks were felt in Japan just several days after the big earthquake in 2011. The 1992 Landers earthquake near Los Angeles triggered aftershocks in 14 different locations. Some of the locations were hundreds of miles away from the main earthquake.
Slide #1-Colorado River Basin
The Colorado River begins in the Rocky Mountains where it is fed by melting snow. The Rocky Mountains serves as a snow storage area, slowly releasing winter and spring precipitation through early and midsummer. As the summer progresses, the snow starts to melt at higher elevations. The Colorado River is like the Nile River. Both the Colorado River and Nile are considered "exotic rivers", which means that the river begins in a humid area, but it runs mostly through arid lands on its journey to the sea. The Nile River is the longest in the world. It drains most of northeast Africa. As it travels through the deserts of Sudan and Egypt it loses a lot of water due to evaporation and ground seepage. It is only the 36th largest river in the world based on stream discharge. The annual flow of the Colorado isn't even in the top 25 rivers in the United States based on annual flow. Runoff from the Sierra Nevada carries ten times the amount of water that the Colorado River does. Exotic streams have very few smaller streams flowing into them and the discharge pattern is opposite that of a normal stream. Instead of the amount of water in the river increasing as it flows downstream, it decreases instead. This is further impacted by water withdrawals, reservoir construction, and high evaporation rates. The United States government built the 9 dams on the Colorado River to try to draw people to the region and "reclaim" the arid lands for economic development. The Desert Southwest was a dam builder's nirvana. It is full of deep, narrow canyons and gaps. The Eastern United States has very few tight gorges for dams. There is also too many people in the Eastern United States that live along the rivers and they would have to be moved when they built a dam. The Desert Southwest was very sparsely populated. The Desert Southwest has large floods because precipitation is very erratic in this part of the country. There is also little or no ground cover to hold the flood waters back. All the water runs off instead of seeping into the ground.
Slide #5-The Desert Southwest
The Colorado River provides over half the water for San Diego and Phoenix. During the 1990s, metropolitan Phoenix was expanding into the surrounding desert at one acre per hour. Phoenix still grows at 3% per year. Arizona's conservative political and business leaders do not want to restrict urban development. Such urban expansion cannot be sustained much longer. Water supplies are nearing their limit. Central Arizona Project Canal transports water across hundreds of miles of desert to Phoenix and Tucson. A lot of water is lost through evaporation, percolation, and leaks in the canals. Las Vegas gets 90% of its water from the Colorado. In Las Vegas, lawn watering is only allowed on 3 arranged days a week and golf courses are now being restricted by strict water budgets. People that violate these water rationing measures are fined. Many people in Las Vegas are replacing their lawns with xerophytic plants. Las Vegas is aggressively looking for groundwater supplies from other sources. They want to pump groundwater in Northern Nevada and build a pipeline to bring it to Las Vegas. Groundwater extraction will dry up lakes killing endangered fish species and will destroy the ranching industry in Northern Nevada. The Colorado River is also responsible for a lot of the nation's fresh winter vegetables. The Imperial Valley in Southeastern California is one of the most productive farming areas in the United States. The Imperial Valley relies on water from aqueducts coming from the Colorado River. The Imperial Valley is a desert that has been transformed into an agricultural oasis by Colorado River water. Farmers in the Imperial Valley actually don't like when it rains because the warm rainwater wilts the lettuce plants.
Slide #23-East African Rift Valley
The East African Rift Valley extends southward from Ethiopia to Mozambique. The East African Rift Valley is on average 500 feet below sea level. Olduvai Gorge in the East Africa Rift is particularly significant because ancient rocks have been exposed in the walls of the widening valley. These rocks contain numerous hominoid fossils. If it wasn't for the East African Rift Valley these fossils would not have been exposed. The volcanoes of Mount Kenya and Mount Kilimanjaro are located near the rift valley. So are a bunch of large lakes like Lake Victoria and the Nile River. The Red Sea separates Africa (Egypt) and the Arabian Peninsula (Saudi Arabia). The spreading has formed a "proto-ocean". It is similar to the young Atlantic Ocean between Africa and South America about 200 million years ago.
Slide #35-Horst & Graben (Tension)
The North American Plate is moving a quarter to a half inch a year towards the west. As North America stretches horsts and grabens develop. Horst- is a fault block that moved relatively upward between two faults or remained in place while an adjacent block slid downward. Graben- is a block that slid downward between two faults or remained in place while blocks on either side slid upward along the faults. An example of a graben is Death Valley. The Basin and Range region of the United States goes from California to Utah and from Oregon to New Mexico. This region is undergoing tectonic forces that are pulling the region apart from east to west (tension). If you drive from Reno to Salt Lake City you will encounter an exhaustive series of alternating down dropped and up thrown fault blocks. Santa Barbra is on a Graben between 2 parallel faults. One of the faults is responsible for the Santa Ynez Mountains. Santa Barba had a very large earthquake in 1925 and several smaller ones since.
Slide #32-Southern California Earthquake Map
The San Jacinto Fault, Elsinore Fault, and Imperial Valley Fault are the most dangerous faults in Southern California outside of the San Andreas. Southern California has 300 faults. The greatest concentration of these faults is in and near the San Bernardino, San Gabriel, and Santa Ynez mountains. These mountains are there because earthquakes are pushing them up. California Falling into the Ocean The movement of the Pacific Plate is about two to three inches a year towards the northwest. As a result, Los Angeles City Hall is now 10 feet closer to San Francisco than when it was built in 1924. Eventually Southern California will break off from the coast of North America, become a large island adjacent to San Francisco, and eventually be subducted down beneath the Aleutian Islands off the coast of Alaska.
Slide #23- Los Angeles Aqueduct
The aqueduct instead was being used by farmers in the San Fernando Valley. Between 1913 and 1927, the San Fernando Valley used 3 times more water than the city. There was a year during that period where the city did not use any aqueduct water at all. Right before the city annexed the San Fernando Valley, people "in the know" bought the dry, dusty San Fernando Valley land very cheaply. These Real Estate Investors (plus the people that bought the Owens Valley land) made a ton of money. Henry Huntington (which Huntington Beach is named for) was one of the key investors in buying up the San Fernando Valley. The owner of the Los Angeles Times bought up a large tract of land in the San Fernando Valley. By the 1920s, the normal dryness returned to Los Angeles. The San Fernando Valley demanded more water from the Owens River. The Owens River completely dried up. The aqueduct turned a farmer's paradise (the Owens Valley) into a desert and a desert (Los Angeles County) into a farmer's paradise. The mood of the farmers in Owens Valley (many who were now leasing their land back from the city of Los Angeles) grew steadily worse. They threatened the aqueduct with sabotage. The head of the Los Angeles Department of Water and Power said, "It is too bad that so many orchards in Owens Valley had died of thirst because there may not be enough trees in Owens Valley to hang the troublemakers". There is a museum in the Owens Valley that tells the history of the aqueduct from the valley's perspective. The museum is located on land leased from the city of Los Angeles. The Owens River Valley economy is very dependent on tourism because it is too dry for farming. All their water is diverted to Los Angeles.
Slide #18-Paricutin Volcano
The hole in the corn field had been there for as long as anybody could remember. Three weeks before the actual eruption, rumbling noise that resembled thunder were heard by people in the nearby area. There had also been a few small earthquakes in the a couple days prior to the eruption. Two farmers who were preparing the field for planting noticed smoke and sulfurous gases coming from the hole. As night fell, hot rocks flew skyward, creating giant arching flares like a fireworks display. The volcano grew five stories in height in a week. Eventually the volcano began erupting and lava flows buried a nearby village except for the top of a church steeple. After 9 years of activity the volcano now lies dormant. The volcano is starting to rapidly erode. Mexico has had quite a few volcanoes. El Chichon killed 1,700 people in 1985. Santa Maria killed 6,000 people in 1902.
Slide #6- The Grand Tetons
The majestic Grand Tetons are formed by faulting action. The Teton Fault is at the break in the slope where the eastern foot of the mountain range joins the flats at the west edge of Jackson Hole. The Grand Tetons are formed by upward movement of the Teton Fault. The base of the Grand Tetons is characterized by steep cliffs and no foothills. The Grand Tetons grow a foot every 300-400 years due to faulting action. Every time there is an earthquake on the Teton Fault the mountain range will rise in elevation. The Teton Fault has produced an earthquake as large as a 7.5 magnitude.
Slide #15-Composite Volcano
The mountain builds up steep sides by having layers of ejected pyroclastic material from explosive eruptions. The pyroclastic material forms steep slopes while the lava flows hold the pyroclastic material together. Hardened lava holds the pyroclastic material together like cement. There are also hardened mudflow deposits on the sides of composite volcanoes. Composite Volcanos can get over 12,000 feet in elevation. Mt. Fuji in Japan, Mt. Rainier in Washington, Mt. St Helens in Washington, Mt. Shasta in California are examples of well know Composite Volcanoes. Composite Volcanoes occur on convergent plate boundaries.
Slide #20-Seafloor Spreading
The ocean floor recycles itself. The midoceanic ridge is a line of volcanoes that spew lava onto the ocean floor. Magma wells up from earth's interior. The mid-ocean ridge contains the newest crust on the planet. The rocks sampled get older as you move away from the midoceanic ridge. There is some very weird looking marine life that clusters near the midoceanic ridge. These strange animals that live at the bottom of the ocean like the heat of the undersea volcanoes. Oceanic crust lasts for 200 million years. Since the earth is not getting bigger, older oceanic crust must be destroyed when the newer oceanic crust is created. The older oceanic crust is subducted and melted. The deep oceanic trenches are where the old oceanic crust is subducted and destroyed. Continental crust is of a lower density and cannot be subducted, once it forms it is virtually permanent. The average age of continental crust is 1 billion years old. Some continental crust has found to be 4 billion years old.
What is a focus in relation to earthquakes?
The point where an earthquake happens
Slide #35-Earthquake Damage
The quality of building construction is very important in how much damage an area sustains. The Chile earthquake released 1,000 times more energy than the earthquake in Haiti, yet killed fewer people. A magnitude 6.5 earthquake struck Central California in 2003 and killed two people in San Simeon who lived in a very old house. Very few other buildings were even damaged. A magnitude 6.5 earthquake struck Iran the same week the earthquake hit Central California. And 30,000 people were killed. 85% of the buildings in the city near the epicenter of the Iranian quake were destroyed. In 2005, a 7.2 magnitude earthquake struck Japan killing nobody. A month later a 7.6 magnitude earthquake struck the India-Pakistan Border killing 79,000 people and leaving 3 million homeless. The Japanese building philosophy used to be to build strong, thick columns and pillars meant to withstand the ground shaking. Not anymore. "No more build like oak tree, but like reed". Buildings now sway with the shaking. Earthquake Predictions Chinese geologists accurately predicted an earthquake due to a flurry of foreshocks beforehand. They evacuated about a million people during the morning and a major earthquake struck later that day. The Chinese government was convinced that they could now predict earthquakes. Chinese geologists started issuing false alarms for cities all over China. They forced people to evacuate their homes for over a month. Eventually the Chinese government stopped trying predict earthquakes because they were very rarely right. In 2005, Japanese geologists were able to broadcast accurate warning signals 16 seconds before a 7.2 magnitude earthquake. These warning signals could in theory trigger a computerized control system to shut off gas lines, high tension electrical transmission lines, sensitive equipment in chemical factories and refineries. This could also warn air traffic controllers about planes landing and alert physicians in surgery. Before an earthquake strikes an area, the level of groundwater often drops. Radon gas in groundwater often rises before an earthquake. There has also been strange animal behavior and unusual radio waves before an earthquake. Scientists are placing GPS receivers on either side of faults to detect any change of position. They will also drill holes in rocks to measure any deformity. In 2012, seven scientists in Italy were sentenced to 6 years in prison for not predicting an earthquake. They were also slapped with huge fines.
valley: created by running water for the most part
between two mountains, a lowland between two mountains. Are almost always caused by the erosive power of a river Some valleys have very steep sides and others have gently sloping sides The bottom of the valley may only covered by the river itself, but usually there is a large, flat area that is dry
Slide #30-Hot Spots
There are about 50 places on earth where magma from deep in the mantle comes to the surface at locations that are not anywhere near plate boundaries. Hot Spots are relatively stationary over many millions of years. Hot Spots help explain the volcanic activity in the middle of tectonic plates. They also reveal the direction of plate movement. As magma rises through the plate above it creates volcanoes. The plate above the Hot Spot is on the move, so the volcanoes are eventually carried off the plume and become inactive. New volcanic features then develop over the Hot Spot, generating a hot spot trail. The Galapagos Islands, the Canary Islands, Easter Island, and Tahiti are located on a hot spot. Hawaii The islands of the Hawaiian chain are progressively younger from west to east. Mauna Loa on the big island is the world's largest volcano; it is 6 miles from its base on the ocean floor to the top of its summit. The big island of Hawaii has grown 500 acres since 1983 because the lava flows from Mauna Loa have added additional soil to the island. Many people assume that the coasts of all Hawaiian Islands are flanked by coral reefs. That is not entirely true. Coral reefs take a very long time to become fully developed. Since the eastern side of the Big Island of Hawaii is relatively young (geologically speaking) it does not feature corals reefs. The island of Loihi is also located on the hotspot and is presently 3,200 feet below the surface of the ocean. Loihi will not break the surface for another 10,000 years.
Slide #21-Plate Tectonics
Think of the earth as a hardboiled egg. The brittle shell is the earth's crust. The slippery inner lining of the shell is the asthenosphere. The egg white is the mantle. The yolk is the core. Before eating a hardboiled egg you break the brittle shell into pieces that slip around as we try to pluck them off. That concept is similar to the theory of continental drift. The continents are not drifting; they are embedded in the thicker lithospheric plates, carried along by the action of seafloor spreading. The tectonic plates float over the hot wax like asthenosphere. The plates vary in size. Many of the smaller plates are remnants of once larger plates being subducted. There are about 14 different tectonic plates. The rate of tectonic plate movement is only 0.5 inches in parts of the mid-Atlantic ridge to 4 inches per year along the Nazca Plate. The average tectonic plate moves 2 inches a year or about as fast as your fingernails grow. The tectonic plates moved faster early in the earth's history because the interior was releasing more heat. The American Tectonic Plate includes most of the continental crust of North America as well as the entire ocean floor lying west of the mid ocean ridge that divides the Atlantic down the middle. It moves at less than 1 inch per year. The Pacific Tectonic Plate occupies much of the Pacific Ocean basin and consists almost entirely of oceanic crust. Its relative motion is north-westerly, so the subduction boundary runs along the northwest edge near Alaska's Aleutian Islands. It moves at 2 inches per year. The distance between New York City and Denver remain unchanged because both cities exist on the North American Tectonic plate. The distance between New York City and Los Angeles is changing because New York City is on the North American Tectonic Plate and Los Angeles is on the Pacific Tectonic Plate. In the 1980s, the US department of defense declassified the data from the network of satellites that form the global positioning system. GPS receivers are permanently fixed to the ground and have tracked the movement of continental drift. The GPS receivers do not move until the ground moves. This has allowed scientists to plot maps of the earth's surface velocities. The GPS data confirms that plates have been moving for the last 20 years.
Slide #34-Tilted Fault Block Mountains
Under certain stresses a surface block may be upthrown on one side without any faulting or uplift on the other side of the mountain. The Sierra Nevada Mountains rise a centimeter to an inch and a half every year due to faulting action. There are not many highways that cross the Northern Sierra Nevada Mountains where mountain passes are often above 10,000 feet in elevation. The eastern flank of the Sierra Nevada Range rises 2 miles in elevation for every 12 miles in distance. The steep eastern flank hindered the migration of people into California during the Gold Rush era. On the western flank the Sierra Nevada Range rises 2 miles in elevation for every 50 miles of distance. The western side has rolling foothills.
Slide #19-Flashfloods in Las Vegas
Urban surfaces are covered by buildings, driveways, sidewalks, pavement, and parking lots. Runoff time is shortened, while to proportion of the runoff is increased by the expansion of impervious surfaces. Many rapidly expanding suburban areas are finding that low-lying, formerly flood free residential areas are now experiencing periodic flooding.
valleys
Valleys are popular sites of settlement. Valleys are flat and have fertile soils which are good for farming. Valleys often have a river flowing through them. The water in the river can be used for household needs and irrigation. Rivers also important transportation networks in most countries.
Volcanoes and Climate
Volcanic ash reflects sunlight back into space The "Year Without a Summer" in 1815 coincided with Mt. Tambora erupting in Indonesia The eruption of Mt. Pinatubo in the Philippines in 1991 caused global cooling for a couple years
Mudflows
Volcanoes release intense heat which quickly melts the snow causing flash flooding The loose mantle of ash and pyroclastic flow deposits on the slope can also be displaced by rain This produces a moving slurry of mud and boulders that move like wet concrete
Slide #9-Volcanic Gas
Volcanoes show increased seismic activity before they erupt. Scientists will also monitor the increase of sulfur dioxide because that is a sign of a potential eruption. Volcanoes will also release large amounts of Co2 which will suffocate small animals. Ash and steam are the first signs of activity associated with a volcano. The rising magma reaches the groundwater below the volcano and produces steam explosions. More volcanic gas means that there is a greater chance of eruption. In Columbia in 1993 a volcano became so plugged by high viscosity magma that it released no gasses or ash before it violently exploded. Six geologists were killed by the volcano while they were recording gas readings on the summit. Popocatepetl (pictured on the slide) is 17,883 feet high and means "smoking mountain" in an indigenous language. It has erupted several times in current history and caused widespread destruction. It was starting to erupt in 1519 as Cortez and his roughly 500 troops marched towards Mexico City. Montezuma interpreted the eruption as an omen from god and it affected his thinking about how to handle Cortez.
Slide #16-Alluvium
Whatever is picked up by a stream must be eventually set down. Stream deposits are found at the mouths of canyons, on floodplains, and along the inside of river bends. Eventually most debris ends up in a lake or ocean. You put your sugar in your iced tea and are stirring it and you get a phone call. When you get back to your iced tea the sugar is on the bottom. When a rivers velocity decreases the clay or silt becomes deposited on the bottom. Sorting of the rocks occurs when the speed of water flow diminishes as stream competence drops. An alluvial deposit is often comprised of particles that are about the same size. Rocks are found alongside the slopes of steep mountain streams. As one continues downstream the stream changes composition from gravel, to sand, fine grained silt, and then mud. Alluvial material is typically smooth and round due to the battering the particles receive from each other.
Slide #9-Exogenic (External) Processes
When the ice mass becomes extremely thick the lower layers become almost plastic like (not brittle) and the ice will start to flow outward or downhill. Glaciers carve distinct deep and wide valleys as they flow downhill. About 7% of contemporary erosion is accomplished by glaciers, which is a small amount compared to fluvial erosion. But considering that glaciers only cover a small land area, the glaciers make respectable contribution to continental erosion.
Slide #25-Oceanic/Oceanic Tectonic Plate Convergence
When two oceanic tectonic plates collide, the tectonic plate with the older crust which is cooler, heavier, and denser, descends into the subduction zone. With time a volcanic island arc develops like the Aleutian Islands and the Philippines. The arc may eventually become more mature and become an arc system like Japan and the islands of Sumatra and Java. Large earthquakes and tsunamis can occur at these tectonic plate boundaries. The distance of the volcanoes from the oceanic trench will depend on the slope of the subduction zone. The volcanic islands are closer to the in steeply inclined subduction zones and are farther away in gently sloping subduction zones.
Slide #28-Earthquakes
While an earthquake can take place at the surface, it can also occur deep below the ground. Most earthquakes occur at a depth where displacement is not visible at the surface. The two sides along the fault are locked in friction, resisting any movement despite the powerful forces acting upon the adjoining crust. An earthquake is essentially a vibration in the earth produced by shockwaves created by a sudden displacement along a fault. Think about bending a wooden pencil until it breaks. At first the pencil bends (deforms). If you keep applying pressure, you know the pencil will suddenly snap, but you don't exactly know when or exactly where the pencil will break. Focus- The subsurface location where the rock displacement occurs is called the focus. This may be as deep as 435 miles in depth. Epicenter- location is where they typically name the earthquake. It is really hard to determine the exact place because sometimes a large portion of the fault moves. The epicenter for the Loma Prieta quake was in the mountains east of Santa Cruz (Loma Prieta Mountains). The 2001 quake in Seattle was called the Nisqually earthquake because the epicenter was located 33 miles below the mouth of the Nisqually River in western Washington. The Northridge Earthquake was located in the city of Northridge. The 1987 Whittier Narrows Earthquake was located in the city of Whittier near the 60 Freeway. Several other factors can affect shaking. Earthquake waves do not travel evenly in all directions from the rupture surface; the orientation of the fault and direction of movement can change the characteristics of the waves in different directions. This is called the radiation pattern. When the earthquake rupture moves along the fault, it focuses energy in the direction it is moving so that a location in that direction will receive more shaking than a site at the same distance from the fault but in the opposite direction. This is called directivity. USA Map Alaska has 57% of the nation's earthquakes and California has 23% of the nation's earthquakes. Nevada has 5% of the nation's earthquakes and Hawaii has 5% of the nation's earthquakes. Any city west of the Rockies is somewhat near a fault. Seattle, Salt Lake City, Las Vegas, Albuquerque, and El Paso are all near faults. Yellowstone Park is also near a fault. The Big Island of Hawaii has earthquakes because the recently cooled lava shelf can crack and fall into the ocean. A 7.2 magnitude earthquake in 1975 on the Big Island caused a 40 foot tsunami which drowned two people who were camping on the beach. The earthquake shaking dies off with distance more quickly in the western United States than in the older and more rigid crust of the eastern United States. Earthquakes in the eastern United States can cause a lot of damage because the shaking is more intense than in the western part of the country. Luckily the eastern part of the United States doesn't have many faults.
Exogenic Processes
Wind is found everywhere on earth, but is trivial in power as a terrain sculptor Wind is ordinarily only strong enough to erode and transport small mineral particles that are loose and dry Wind erodes deserts, beaches, and plowed fields
Big Thompson Canyon
Winds from the east pushed very humid air up the Rocky Mountains The river upstream received almost a foot of rain in less than 4 hours The flood waters got 19 feet high 139 people died, 418 houses were destroyed, and many other buildings were damaged
Transform
In this boundary plates slide past each other.
Convergent
In this boundary the plates come togehter.
Divergent
In this boundary the plates move away from each other.
What is a destructive plate boundary like?
It is where a continental plate and an oceanic plate move towards each other
Give an example of a devastating earthquake in an LEDC
Haiti 2010
Subduction
At a convergent convergent boundary where an ocean meets a continent, the ocean dives under. This is called BLANK>
Why did such a thick ash cloud form from that particular volcano?
It was buried under a thick layer of ice which fragmented the lava
Where is Haiti in the world?
On the island of Hispaniola in the Caribbean ocean
Exogenic Processes
Running water shapes the Earth's surface more than all other exogenic agents combined Running water causes 90% of contemporary erosion Running water decreases the elevation of the land and deposits the sediment in flat areas or on the ocean floor.
Sea floor spreading
Sea BLANK BLANK creates midocean ridges, earthquakes, and volcanic activity.
Theory of Plate Tectonics
Theory that plates that move due to convection currents
