Geology Exam
The three steps of natural ozone production and destruction in the stratosphere
(i) O2 +UV -> O+O(+heat) (ii) O2 + O -> O3 (iii) O3 + UV -> O2 + O (+ heat) UV radiation is converted from light to heat by the destruction of oxygen molecules and ozone molecules. Temperature rises with increasing altitude in the stratosphere.
(chapter 17)
(last day of class)
volcanic gases
(water vapor, sulfur dioxide, carbon dioxide) may affect climate patterns − Sulfur dioxide may block insolation, temporarily (up to 1 year) reducing global temperatures
Maps with Isobars and contours of pressure
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still need to finish ch17 notes
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Concentrations are
- nearly constant over the tropics. - more concentrated with larger seasonal variations at higher latitudes - greatest in Northern Hemisphere during its spring - greatest in Southern Hemisphere during Northern Hemisphere fall - linked to atmospheric circulation patterns, temperature, and solar radiation reaching the Earth.
Greenhouse Gases and Global Change
-Infrared radiation emitted from Earth's surface is absorbed by water vapor, CO2, and other trace gases in the troposphere, creating a situation known as the greenhouse effect. -We like it because it keeps the average surface temperature of Earth ~59°F as opposed to 0°F. -Can have too much of a good thing - Venus has runaway greenhouse effect with average surface temperature of 885°F. -Facts: -The 20th century was the warmest in the last millennium -There have been 5 new "hottest year" records set since 1992. -The last "coldest year" record was set back in 1916. -There may be a debate about the severity of global warming, but one trend is undeniable - The concentration of greenhouse gases in the Earth's atmosphere has steadily and measurably increased over the past two centuries.
CFCs and Ozone
-Ozone is naturally reduced above Antarctica every spring, but reductions beyond the expected natural variation were noticed in 1985. -Ozone hole - not an actual hole, just an area of reduced ozone. -Ozone levels began to drop in the 1970's. -During October (Southern Hemisphere spring) ozone concentrations over Antarctica drop to ~100 DU.
chlorofluorocarbons (CFCs)
-Volatile organic compounds used as aerosol propellants and refrigerants -Inert (don't react with other gases in the atmosphere) and therefore remain in the atmosphere for up to 200 years -Can be broken down by photolysis (UV radiation) which frees chlorine atoms from the CFCs -Chlorine atoms react with ozone destroying an ozone molecule and creating chlorine monoxide and oxygen: Cl + O3 -> ClO + O2 Chlorine monoxide reacts with oxygen atoms freeing up another chlorine atom available for breaking down ozone 80% of chlorine in the stratosphere comes from CFCs In 1978, per the Montreal Protocol, the US banned aerosol sprays containing CFCs and phased out their production
Non Silicate Minerals
-carbonates -sulfates -sulfides -oxides
Igneous Rock composition defined by
-felsic-mafic (iron + magnesium rich minerals) -color -silica content
Solar Radiation
-most is what we can see/visible light (47%) and infrared (45%) -> absorbed before it's on earth b/c of greenhouse gases
Viscosity and temp
-viscosity decreasing as temp increases -air, water, canola oil, motor oil, corn syrup, basalt lava, peanut butter, andesite lava, tar, rhyolite lave (least to most viscous)
Active volcanoes
1,500 active volcanoes worldwide
The speed of plate motion is approximately
1-10 centimeters per year
The speed of plate motion is approximately (repeat exam 1)
1-10 centimeters per year
formation of the Ozone layer is cyclical
1. UV radiation breaks an O2 molecule into two separate O atoms. 2. An individual O atom combines with a whole O2 molecule to form an ozone molecule. 3. UVB strikes an ozone molecule and breaks it back down into an O2 molecule and an O atom. This O atom is then free to combine with another O2 and make more ozone. No long-term change in the concentration of ozone occurs.
Ice Ages + their possible causes
1. changes in Earth's orbit -going around sun, orbit (eccentricity) is more oblong + can ∆ through time, which ∆s polarity that the earth receives *2. ∆s in the greenhouse gas content of the atmosphere -stronger the tilt, stronger the seasons *3. ∆s in the reflectivity (albedo) of the planet -whatevers coming from the sun is going back out into space w/out touching earth b/c of reflectivity of the planet 4. disruption to global wind or ocean circulation patterns -amplify the small ∆s that affect earth
The amplitude (size) of the seismic waves generated by a Moment magnitude 7 earth- quake is approximately times greater than the amplitude of waves produced by a magnitude 6 earthquake.
10
How large would an asteroid have to be to generate a 200 km diameter impact crater like the Chicxulub crater on Mexico's Yucatan Peninsula?
10-20 km in diameter
How large would an asteroid have to be to generate a 200 km diameter impact crater like the Chicxulub crater on Mexico's Yucatan Peninsula?
10-20 km in diameter
The amplitude (size) of the seismic waves generated by a Moment magnitude 6 earth- quake is approximately times greater than the amplitude of waves produced by a magnitude 4 earthquake.
100
If radioactive decay begins with 800,000 parent isotopes atoms, how many will be left after three half-lives?
100,000
Approximately how old is the oldest oceanic crust scientifically dated to be?
200 million years
Compounds
A combination of two or more chemical elements in particular proportions that have distinctive physical properties
Consider the 26 December, 2004 Indonesia earthquake where over 200,000 people died. Many people were killed who lived along the coast of the Indian Ocean, tens to hundreds of miles from where the earthquake initiated the resulting tsunami. If there had been an adequate tsunami warning system, how much time would there have been to get those people to higher ground?
A few minutes to a few hours
In order for a substance to be considered a mineral it must have all of the following characteristics except
A) Solid B) Naturally occurring C) Definite chemical composition D) Orderly internal arrangement of atoms ANSWER: E) Organic in origin
Partial melting of mantle wedge generates...
ANDESITIC magma with MED silica content
When did large numbers of fossils first appear in the geologic record?
About 500 million years ago
Air pressure
Air pressure declines with increasing altitude. Pressure is force per unit area more pressure as you get closer to earth's surface
After many millions of years, the relative movement of the Pacific and N. American plates will move Los Angeles (on the Pacific plate) closer to
Alaska
Ion
An atom that is positively charged or negatively charged
Where are the deepest earthquakes generated?
At subduction zones
Where are the deepest earthquakes generated? (repeated exam 1)
At subduction zones
Partial melting of asthenosphere generates...
Balsaltic magma with LOW silica content
The name for the type of rock formed at midocean ridges is  . (Hint: this rock is dense, and makes up most of the ocean crust)
Basalt
Lava, Silica, and Viscosity relationship (KNOW THIS)
Basalt (low silica= low viscosity)- high temp Andesite (med silica= med viscosity)- med temp Rhyolie (high silica= high viscosity)- low temp
Why do some scientists suggest that we are living in a new period of Earth history called the "Anthropocene"
Because humans are causing significant changes to the planet.
Suppose you find a rock made up of mostly of decayed plant material. What type of rock have you found
Biochemical
How would an extinction affect biodiversity?
Biodiversity decreases after a major extinction event.
Which component of the earth system relates to all living things on earth?
Biosphere
The primary reason there are seasons on Earth is because
C) the spin axis of Earth is tilted with respect to the plane of Earth's orbit around the Sun.
What evidence indicated that Mount St. Helens was going to erupt?
Changes in shape; Earthquakes; Gas emissions -> all of the above
Three types of sedimentary rocks
Clastic,Chemical,Biochemical
clastic sediment
Clay, Silt, Sand, Gravel (smallest to largest)
Mineral Physical Properties
Color Hardness Cleavage Luster Density Crystalline Form
Clastic Sedimentary Rocks
Composed of rock and mineral fragments
Which two ideas were combined to form the theory of plate tectonics
Continental drift and seafloor spreading
Which two ideas were combined to form the theory of plate tectonics?
Continental drift and seafloor spreading
What type of plate boundary is most likely to generate a tsunami? (repeated exam 1)
Convergent
MAJOR MASS EXTINCTIONS IN HISTORY
Cretaceous-Tertiary (K-T) extinction + Permian-Triassic (P-T) extinction
What type of material forms most mountains?
Crustal material
Concentration is measured in what unit?
Dobson Units -a typical concentration for the region (layer) is 300 Dobson units
EXAM 1
EXAM 1
EXAM 2 CORRECTIONS
EXAM 2 CORRECTIONS
EXAM 2 PRE
EXAM 2 PRE
EXAM 3 NOTES
EXAM 3 NOTES
Erosion & Transportation Clastic Sedimentary Rocks
Erosion-> Sediment moved from place of origin by streams, wind, glaciers
What causes volcanic eruptions?
Escaping volcanic gases -gases (water vapor, co2, sulfur dioxide) are dissolved in magma
A hypothesis is supported by more scientific observation and research than a theory.
FALSE
Simple impact craters have a central peak, unlike complex craters.
FALSE
Temperatures on Earth would be higher if there were less carbon dioxide in the atmo- sphere.
FALSE
Plutonic rocks form at or very near the surface.
False
Temperatures on Earth would be lower if there were more carbon dioxide in the atmosphere.
False
Biochemical Sedimentary Rocks
Form due to actions of living organisms that cause minerals to be extracted from solution The mineral calcite is present in the rock limestone formed by coral organisms that build tropical reefs May form from the remains of dead organisms
Chemical Sedimentary Rocks
Form when minerals precipitate (crystallize) from a solution as a result of changing physical conditions Canbereadily dissolved in water and transported to oceans Salt like
Which of the following is a low silica rock which cooled slowly
Gabbro
Poisonous volcanic gases from Lake Nyos, Cameroon, killed 1,700 people in surrounding villages (1986)
Gases from Volcano eruptions can be dangerous... bodies of water can even hold these in
Caldera
Giant crater formed from collapse of volcano into underlying magma chamber
Which of the following is a high silica rock which cooled slowly
Granite
Silica Content (Plutonic Rocks)
Granite (high), Diorite (medium), Gabbro (low)
Cambrian "explosion" (542-488 Ma) Explosion of organisms with hard skeletons at beginning of Cambrian
Hard parts can be easily preserved as fossils.
18th century - James Hutton (relative time)
He observed that The landscape remained unchanged with the passage of time. DEDUCTIONS: 1. it takes a long time to influence the Earth's surface significantly (Uniformitarianism) 2) All land should be worn flat (erosion) unless some process renews the landscape by forming new mountains (cyclical change).
cold + warm regions in relation to air pressure
Highest air pressures are found in cold regions, lowest air pressures are found in tropical warm environments. Compressed air becomes warmer, expanding air becomes cooler
Magma Viscosity
How easily gases escape from magma is controlled by magma viscosity
Rocks in 3 categories
Igneous Sedimentary Metamorphic
Geologists can correlate sedimentary rocks by comparing the fossils found within the rocks
Index fossils: species that existed for a relatively short period of geologic time and found over large geographic areas are the best for precise correlations.
What happens to a mountain root as erosion removes material from the summit?
It gets shallower
Ozone & Global Temperature Relation
It is a common misconception that ozone depletion causes global warming. However, both are global- scale issues related to atmospheric composition - ozone in the stratosphere, and CO2 and some other greenhouse gases in the troposphere.
The difference in the arrival times of the P and S waves at a seismograph station allows you to determine what about the earthquake?
Its distance from the seismograph station
Which statement comparing terrestrial and Jovian planets in our solar system is most accurate?
Jovian planets are larger and less dense than terrestrial planets.
Higher viscosity lava remains within volcano crater
Lava dome formed in crater of Mount St. Helens
Chapters 11, 13, 16
Lectures 18-26
This earthquake-generated hazard can occur when seismic waves shake water-saturated soils.
Liquefaction
40. Many things can happen when a large NEO strikes Earth. Consider only ejecta for a moment. How and why would ejecta affect short term climate (over a few months)
Lower global temperatures by blocking incoming energy from the Sun
Suppose three identical magnitude 3 earthquakes occur in three different locations. The epicenters are Anchorage (Alaska), Los Angeles (California) and Boston (Mas- sachusetts). Which location would most likely experience the largest intensity the farthest from the epicenter?
Massachusetts
What is the order of planets, from closest to the Sun to furthest from the Sun?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Rocks that are formed by the crystallization of new minerals in the solid state (i.e. without melting) due to heat and/or pressure are
Metamorphic
Rocks are formed from...
Minerals (solid aggregate of one or more)
Minerals
Naturall occurring inorganic solid element or compound definite chemical composition regular internal crystal structure identified by physical properties
Where are the youngest seafloor rocks found
Nearest the mid-ocean ridges.
Where are the youngest seafloor rocks found?
Nearest the mid-ocean ridges.
______ faults are most common at divergent plate boundaries.
Normal
Energy emitted by the Sun is produced by
Nuclear Fusion
What was the name of the super-continent landmass proposed by Alfred Wegener, who formulated the idea of continental drift
Pangaea
first stages in formation of clastic sedimentary rocks (generation)
Physical and chemical breakdown of any rock at Earth's surface (weathering) to form sediment
17th century Nicholas Steno's Principles of relative time
Principle of original horizontality + Principle of superposition
Partial melting of continental crust generates...
RHYOLITIC magma with HIGH silica content
Why are mountains there?
Reverse faults stack up and thicken the crust along convergent plate boundaries
Silica Content (Volcanic Rocks)
Rhyolite (high), Andesite (medium), Basalt (Low)
Why are scientists expected to publish the data they use to make discoveries
Science is based on empirical observations
Deposition & Lithification
Sediment deposited when velocity of transport medium decreases Over time, sediment is slowly compacted and grains are cemented together to form a new rock (lithification)
Rocks formed at the Earth's surface from the breakup of other rocks are:
Sedimentary Rocks
How long have asteroids been striking Earth?
Since the Earth formed.
Which type of volcanoes are most likely to explode and why?
Strato - because the magma is more viscous than shield volcanoes
Mt St Helens is what type of volcano
Stratovolcano
Mineral Luster, streak
Streak - color of mark on unglazed porcelain − Example: brown streak of hematite (iron mineral) Luster: how light reflects from mineral − Example: metallic luster of iron pyrite
HISTORY OF RELATIVE TIME GEOLOGICALLY- important principles
Superposition - rocks at the bottom are the oldest. Cross-cutting relationships - older rocks may be cut by younger rocks or features. Inclusion - Younger rocks may incorporate pieces of older rocks.
Inductive reasoning uses specific observations to reach a general conclusion.
TRUE
NEO hunters are not actively searching for smaller objects that could destroy entire cities, but instead are focused on detecting larger objects that could threaten entire countries or continents.
TRUE
Rocks near faults can deform before they rupture.
TRUE
The polarity of Earth's magnetic poles has reversed in the past.
TRUE
Mineral Hardness
Talc (1) to Diamond (10)
What happens to an air parcel as it rises in elevation within the troposphere?
Temperature and pressure decrease
Recall Joe Kittinger's descent: His balloon expanded on his ascent. Why?
The air pressure outside was decreasing leading to an expansion of the helium inside the balloon.
The Greek philosopher Aristotle, like many people at his time, believed the Earth was the center of the universe and that other planets revolved around our own. What is the name given to this ancient concept?
The geocentric orbit hypothesis
What does the Moment magnitude scale measure?
The magnitude of the Earth shaking during an earthquake.
What does the Moment magnitude scale measure? (repeated exam 1)
The magnitude of the Earth shaking during an earthquake.
What determines the atomic number of an element?
The number of protons
What must be true of a rock unit that is cut by an igneous intrusion?
The rock unit must be older than the intrusion
What happens to the depth of the seafloor moving away from a mid-ocean ridge?
The seafloor deepens away from the ridge.
Why are radioactive elements useful for determining the ages of rocks
Their half lives do not change over time
Evaporation and condensation are extremely important.
They contribute to weather phenomena and redistribution of heat in the atmosphere.
What scale predicts the potential threat posed by an asteroid impact?
Torino
What scale predicts the potential threat posed by an asteroid impact? (repeated exam 1)
Torino
Complex impact craters have a central peak, unlike simple craters.
True
Inductive reasoning uses specific observations to reach a general conclusion. (repeated exam 1)
True
Paleontologists have examined the fossil record to determine that over 99% of all species that ever existed are now extinct.
True
3 types of Ultraviolet radiation
UVA, UVB, UVC
Dangerous Volcanoes
Volcanic mudflows from the 1985 eruption of Nevado del Ruiz volcano, Colombia killed more than 23,000 people
Water in atmosphere
Water is constantly cycled through the atmosphere.
Which processes would change an igneous rock to a sedimentary rock?
Weathering, transport, deposition, and lithification
When it was first proposed, Alfred Wegener's continental drift hypothesis was heavily criticized by earth scientists. What was one of their primary objections to the conti- nental drift hypothesis?
Wegener did not offer an explanation for how the continents move.
cold and warm air
When cold air moves over warm water, some of the warm water evaporates (steam fog)
What is a subduction zone?
Where one lithospheric plate is dragged or pushed below another lithospheric plate.
subduction zone
Where one lithospheric plate is dragged or pushed below another lithospheric plate.
Rise and Fall of Mountains
as mass is removed, they will float lower (wood block example); if mass is added, it'll float higher
Where is seafloor returned to the mantle?
at subduction zones
reading elements on periodic table
atomic number; chemical symbol; atomic number
Isostasy
balance between topography of Earth's surface and thickness and density of underlying rocks − Higher mountains with thicker or less dense rocks
UVA and UVB radiation
cause skin cancer and wrinkles after repeated long-term exposure -UV rays can penetrate through your clothes
two fundamental characteristics of a mineral
chemical composition and crystal structure
Mud volcano
chemical reactions convert rock to clay
• Lithification:
compacting the sediments with burial and cementation of the sediments forming a sedimentary rock Gravity plays a role in the formation of all sedimentary rocks. Sedimentary rocks form as horizontal layers (beds)
What type of plate boundary is most likely to generate a tsunami?
convergent
most active volcanoes are found near what boundary?
convergent
What is the proper order of Earth's compositional layers from the surface, where we live, down into the interior?
crust, mantle, core
What is the proper order of Earth's compositional layers from the surface, where we live, down into the interior? (repeat exam 1)
crust, mantle, core
The terrestrial planets, along with the Moon, all have
crusts, mantles, and cores
Gases are released when pressure...
decreases (think of it like a carbonated drink)
Pyroclastic flow
dense cloud formed from combination of tephra and volcanic gases
Ozone Layer
earth's own sun block system that protects us from the ultraviolet radiation
Ionic Bond
electrical attraction of oppositely charged atoms
Mass extinctions
events in which large numbers of species die. -rocks are very different before and after
Principle of superposition
for an undeformed sequence (stack) of rocks, the younger rocks overlie the older rocks.
Plutonic rocks
form if magma cools inside earth's crust (doesn't flow onto surface); coarse crystals will grow
Volcanic Rocks
form if magma flows onto surface as lava (glass often forms)
Covalent Bonds
formed by Elements bonding because of electrical attraction, forming ionic bonds, or the atoms may share electrons -sharing of electrons between elements -like H2O
Which component of the earth system relates to the solid earth?
geosphere
Hot spring
heated groundwater rises to surface
______ is the most abundant element in the Sun.
hydrogen
In the context of science, how would you classify the following statement? Dinosaurs became extinct because a large asteroid collided with Earth.
hypothesis
(graphing relations of rocks) -such as superposition and cross-cutting
igneous- lava cooled rocks metamorphic- rocks formed from heat and pressure Sedimentary Rocks- pebbles and rocks loose on the surface
temperature rises with _____ altitude in the stratosphere
increasing
What happens to the density of air with increasing elevation in the atmosphere?
it decreases
UV radiation is converted from _____ to _____ by the destruction of oxygen molecules and ozone molecules
light; heat
Coquina
limestone formed from broken shell fragments
Volcanic Explosivity Index (VEI)
measures volume of erupted material
Rhyolitic magma
melting of parts of continental crust (oceanic + land rocks) -divergent plate boundary + oceanic hot spot
Mineral Cleavage
minerals break along planes of weakness defined by atomic structure -Example: mica forms sheets joined by weak ionic bonds − Example: feldspar has 2 cleavage planes that intersect at 90 degrees − Example: amphibole has 2 cleavage planes that are not at 90 degrees to each other
Native Elements
minerals composed of single element
Magma v. Lava
molten rock below surface v. at surface
Magma
molten rocks and minerals -Magma is rich in silica
Lahars
mudflows formed when volcanic debris mixes with streams or melting ice
Where is seafloor returned to the mantle
near deep sea trenches
Anion
negatively charged, because it has more electrons (-) than protons (+)
atmosphere is made mostly of
nitrogen and oxygen
Isotopes
number of neutrons for an element may not be the same; variable numbers of neutrons possible -more neutrons = heavier -less neutrons = lighter
Atomic Mass Number
number of protons and neutrons in the element's nucleus
Partial melting
occurs when some minerals in a rock melt while others remain solid Minerals with lowest melting temperatures will melt first -Silica rich minerals have lowest melting temperatures -generates a more silica-rich magma than the parent rock
observing + measuring physical and special properties through...
our eyes
Andesitic magma
partial melting of mantle rocks (with water) at subduction zone -convergent, oceanic trench, subduction zone
Basaltic Magma
partial melting parts of asthenosphere below oceanic ridge or hot spots (not that much silica) -divergent plate boundary
why does silica content vary?
plate tectonics + setting in which silica is made
Protons
positively charged inside the nucleus; number of protons determines the chemical element and the atomic number
Cation
positively charged, with more protons (+) than electrons (-)
tephra
represents particles blasted into air by eruption
Viscosity
resistance to flow -depends on temp + magma composition -magma composition varies w/ plate tectonic setting
Pressure on magma decreases as magma...
rises toward the surface
Igneous Rocks
rock formed by the solidification and crystallization of a cooling magma -Usually composed of silicate minerals and some dissolved gases and water
Principle of original horizontality
sedimentary rocks are deposited in nearly horizontal layers.
UVC radiation
shortest wavelength, most dangerous, filtered out by atmosphere
Atoms
smallest particle into which an element can be divided while still retaining the chemical characteristics of that element =composed of a nucleus surrounded by electrons (nucleus made of protons and neutrons) =neutrons are neutral -protons positive -electrons negative
Ozone earth layer?
stratosphere
elements
substance composed of atoms with the same number of neutrons
The Greenhouse Effect
surfaces on earth absorb solar radiation and re-radiate it as infrared (long wavelength) radiation.
Mineral composition analyzed through...
technology
measuring mineral crystal structure and symmetry through...
technology
trace fossils
tell us something about the organisms that left them behind.
Dew Point
temperature air must reach in order to become saturated.
Latent heat
the amount of heat absorbed or released as water changes state. absorbed during melting, evaporation, or sublimation (solid to gas). released during freezing, condensation, or deposition (gas to solid).
Geological Time
the bottom layer was deposited first; top layer deposited last
Which diagram below best illustrates the concept of isostacy and mountains?
the crust is flat then arches up and then flattens; the mantle is flat then arches down and then flattens
The focus of an earthquake is
the point on the fault surface where seismic energy is first released.
The focus of an earthquake is (repeated exam 1)
the point on the fault surface where seismic energy is first released.
The primary reason there are seasons on Earth is because
the spin axis of Earth is tilted with respect to the plane of Earth's orbit around the Sun.
Half-life
the time it takes for half of the parent isotopes to convert to daughter atoms.
What happens to the age of the Hawaiian Islands moving away from the hot spot
they get older
Most of the mass of the atmosphere is located in which layer?
troposphere
atmosphere is made of the
troposphere and stratosphere
COLOR (igneous)
varies with silica content -high silica are light-colored (ex: quartz) -low silica are dark colored (ex: mica)
Silicate minerals
variety of compounds based on silicon and oxygen -quartz -feldspar -mica -clays -Silica tetrahedron (Silicon with 4 oxygens surrounding) -isolate and chain silicate structures
Cascade mountains
volcanic arc in pacific northwest
Fumerole
volcanic gases escape in absence of water
Geyser
water heated under pressure with volcanic gases
sedimentary rocks
weathering of pre- existing rocks and minerals loose, unconsolidated accumulations of mineral or rock particles loose, unconsolidated accumulations of mineral or rock particles
Foliation
when a rock is subjected to directed stress, its minerals form elongated/platy crystals and line up parallel to each other
Metamorphic Rocks
• "Changed form" rock • formed from pre-existing rock or minerals • Heat, pressure, and chemically active fluids cause changes in rock
Major products of volcanic eruptions
• Airborne - lateral blast, tephra, volcanic gases • Flows on land - lava, pyroclastic flows, lahars
Shield volcanoes
• Broad, gentle slopes • Built from many low viscosity lava flows (basalt) • Relatively mild eruptions associated with hot spots, divergent plate boundaries
More viscosity = More violent eruptions
• Gases escape easily during mild eruptions with low viscosity magma, e.g., Hawaii • Gases escape explosively from high viscosity magma, e.g., Alaska
Stratovolcanoes
• Most common volcano type • Steeper slopes built from alternating layers of tephra and medium viscosity lava (andesite) • Form on plates overriding subduction zones at convergent plate boundaries
Three types of volcanoes
• Shield, stratovolcanoes, cindercone
Cinder cone volcanoes
• Smallest volcanoes, up to 400 meters elevation • Built from more viscous magma products (coarse tephra) • May form on slopes of shield or stratovolcanoes
Why is ozone depletion concentrated over Antarctica?
• Unique weather patterns over Antarctica - polar vortex • Temperatures below -112°F June through August • Leads to formation of polar stratospheric clouds (water + nitric acid) • Ice particles in these clouds provide surfaces on which chemical reactions can occur, including the release of chlorine by chlorine bearing compounds • In spring (September through November) temperature rises, processes that produce ozone outpace destruction and ozone begins to increase • Fewer or no polar stratospheric clouds elsewhere means less ozone loss elsewhere
Mineral Colors
− Dark minerals (black, brown, dark green) § Olivine, amphibole, pyroxene, biotite mica − Light minerals (white, gray, pink) § Quartz, feldspar, muscovite mica, calcite
Sedimentary Rocks 3 stages of formation
− Generation(weathering) − Erosion&Transportation − Deposition&Lithification
VDAPscientiststraveledto Congo to examine eruption of Nyiragongo volcano (2002)
− Lava flowed through the nearby city of Goma (450,000 residents) − Fortunately, toxic volcanic gases trapped in Like Kivu were not released
Mountainsinfluenceclimate patterns
− Monsoon rains strip carbon dioxide from atmosphere − Removal of CO2 has been going on for 20 Myrs − Reduction of this greenhouse gas has lowered global temperatures by ~5oC
Mt. St. Helens eruption
− Volcanoes formed above subduction zone where Juan de Fuca plate slides beneath North America − Mount St. Helens is most active volcano in conterminous US -early on the shape of mountain began to change, creating more earthquakes; eventually earthquake created landslide and magma erupted -reduced height of volcano
