Science Final Exam
Hot spots
These occur where the lithosphere moves over mantle plumes, producing volcanoes
What do diamonds and graphite (pencil lead) have in common?
They are both made entirely and only of carbon
How do we optimize placement of wind farms?
We can optimize placement of wind farms using climate and atmospheric circulation data (you want regular strong winds)
meandering stream
a stream with a channel that curves or loops back and forth on a wide floodplain
desert pavement
a surface of coarse cobbles and pebbles.
Renewable vs. Nonrenewable Resources
renewable - soil, forests, solar energy, fresh water nonrenewable - fossil fuels, coal, oil, natural gas
Fairweather wave base
the area on the bottom of the ocean that is disturbed daily by shallow water waves, given average wave conditions in an area
packrat middens
the composition of middens tells us about changes in species abundance, and changes in plant communities
Biostratigraphy
the correlation of units through time using fossil content
crest
Highest point of a wave
What property determines that most continental crust is above sea level?
Isostacy
Seawalls
(as in Galveston, Texas). Build a big wall! Problem: you lose your beach. Energy is focused in front of the wall, and sand is eroded away
Superposition
-Stacking of strata takes place according to age -The oldest sediment/rock should be on the bottom and the youngest sediment/rock should be on the top
What happens to the concentration of organic matter change as we move downwards through soil into the Earth?
It decreases
trough
Lowest point of a wave
Weathering streams
Streams weather the material (bedrock or sediment) that they flow over via: a. Abrasion b. Turbulent flow c. Dissolution
Things we can measure: stream discharge:
-The Amazon, which is the biggest river on Earth, releases 200,000 CMS (cubic meters per second) or 7 million CFS (cubic feet per second) of flow. -This is 1/5th of the world's freshwater stream flow -One day's discharge would satisfy NYC's freshwater needs for over 5 years
Loma Prieta Earthquake (transform)
-1989, M 6.9. "World Series Earthquake", first major US earthquake to be broadcast on TV! -Quake caused extensive damage -Loma Prieta and the 1906 San Francisco earthquake make the top twenty list of most expensive earthquakes globally on record -This was the wake-up call for California to really enhance quake preparation and planning -The west coast of North America is part of a very complex plate setting
Where do we overdraw our groundwater budget in the United States?
-51% of US population and 99% of rural US population rely on groundwater for drinking water. -64% of groundwater that is withdrawn is used for irrigation to grow crops. -Other uses: industrial processes, irrigation, mining, livestock, aquaculture, energy production. -These figures vary from year to year, but groundwater is a critically important resource! -overbudgeting occurs when discharge is greater than recharge - areas in the US that have heavy groundwater withdrawals: California, the west
what percentage of greenhouse gases are absorbed by the oceans and forests?
-55% are absorbed by oceans and forests -45% remains in the atmosphere (as evidenced by the Mauna Loa curve)
San Andreas Fault (transform)
-A continental transform boundary -The recent (2010) big Haiti earthquake also occurred on a transform boundary -Characteristics associated with terrestrial transform faults include linear features and offsets and shallow earthquakes
alluvial fan
-A fan-shaped deposit of sediment formed when a stream's slope is abruptly reduced -is an accumulation of sediments shaped like a section of a shallow cone, with its apex at a point source of sediments, such as a narrow canyon emerging from an escarpment -form at the mouths of canyons and playa lakes (ephemeral lakes) form in the flat central area of undrained desert basins
Dip-slip Fault
-A fault in which the movement is parallel to the dip of the fault -One of the sides moves vertically (up or down) relative to the other side
African Rift Valley (divergent)
-A new ocean basin is being born at this location -As a result, we see the development of horsts and grabens: these down-dropped blocks result from the plates pulling apart as the rift widens -We get parallel faults (breaks in the ground surface) across the rift as well (these are normal faults)
Metamorphic rock
-A sedimentary or igneous rock that has undergone high temperature or pressure, but has NOT melted all the way -Forms by heat and pressure of a rock
Strike slip fault
-A type of fault where rocks on either side move past each other sideways with little up or down motion -Occurs at a transform boundary
Normal Fault
-A type of fault where the hanging wall slides downward; caused by tension in the crust -Occurs at divergent boundary
Reverse/Thrust Fault
-A type of fault where the hanging wall slides upward; caused by compression in the crust -Occurs at convergent boundary
Sedimentary rock
-A type of rock that forms when particles from other rocks or the remains of plants and animals are pressed and cemented together -Aggregates of smaller grains
What do hot spots tell us about?
-Although most hot spots occur far from plate boundaries, they offer a way to measure plate movement -This is because a hot spot generally stays in one place while the tectonic plate above it keeps moving -At a hot spot, the heat from the plume partly melts some of the rock in the tectonic plate above it
How do you distinguish between anticlines and synclines?
-Anticlines and synclines are the up and down folds that usually occur together and are caused by compressional stress -Anticline: older in center (dome) -Syncline: youngest rock in center (basin) -Anticlines are folds in which each half of the fold dips away from the crest -Synclines are folds in which each half of the fold dips toward the trough of the fold -You can remember the difference by noting that anticlines form an "A" shape, and synclines form the bottom of an "S"
Isotope
-Atoms of the same element that have different numbers of neutrons -Many isotopes are not radioactive. Some isotopes, however, are radioactive! They will change over time into a new form
Where is sediment in motion on the beach?
-Beaches are incredibly high-energy environments, and are made up of sand that has been eroded either from farther inland or from erosion of the coastline and then transported to the beach -Beaches also are constantly changing, and changes are predictable from day to day and from season to season -In the summer, gentler wave action leads to an accumulation of sand deposits on beaches -Whether or not waves feel the bottom determines how and if they interact with sediment -Close to shore and along the shore on the continental shelf, areas will experience wave action frequently -Farther out on the continental shelf and in the deep ocean, some areas will never experience wave action
How can we locate earthquakes using body wave arrival times?
-Because P and S waves have different travel speeds (S waves are slower) -We record their arrivals with instruments called seismographs, which produce seismograms (the records of ground motion) -As distance from an earthquake increases, the distance in arrival time between P and S waves also increases -We can therefore look at seismograms and gauge our distance from where an earthquake originated
P waves
-Body wave -Compressional (material is pushed) -FASTEST -A type of seismic wave that compresses and expands the ground -Deflected in interior of Earth when traveling through outer core
S waves
-Body wave -Shear (material shears back and forth) -A type of seismic wave that moves the ground up and down or side to side -SECOND FASTEST -Cannot travel through liquids (including the liquid outer core)
What does weathering do?
-Breaks material down -Both physical and chemical weathering work together to shape our landscapes -Breaks down bedrock and produces layered soil
What are the two different ways that we classify the outer layers in the Earth (crust/mantle versus lithosphere/asthenosphere)? How do crust and lithosphere differ?
-By their density and composition -We classify the outer layers between chemical and mechanical -The crust and lithospheric mantle is a solid layer with variable composition -Mantle is relatively uniform -Lithosphere moves around on asthenosphere (squishy and hot, what the tectonic plates slide around on) -Crust is a chemical term, lithosphere is a mechanical term
Hydrothermal Metamorphism
-Chemical alteration occurs due to the addition of hot, iron rich fluids that circulate through fissures and cracks which develop in rocks -We see this predominantly along the mid-ocean ridge, where new crust is forming
How do continents grow, and what is a terrane? Know the different things that we can accrete onto continents to grow them.
-Continents grow through time as the result of accretion (small fragments of material collide and merge with continental margins), which occurs due to plate tectonic processes -Terrane: crustal fragments with geologic histories distinctive from that of adjoining terranes -We can accrete: island arcs, microcontinents, and oceanic plateaus -They literally crash into the sides of continents and suture them on
Coastal deserts
-Cool air over cold ocean water holds little moisture because there is little to no evaporation -AS the dry air moves over land, it absorbs any moisture that is present due to evaporation and carries it away
Igneous rock
-Cooled from molten material -Form from either magma (molten material in the Earth-these are intrusive) or lava (molten material that reaches the Earth's surface-these are extrusive) -All igneous rocks are the result of melting at depth, possible fractionation/assimilation as melt rises (more on these terms shortly), and then the cooling of molten material either below (intrusively) or at the Earth's surface (extrusively)
Contact or Thermal Metamorphism
-Country rock is baked by injections of magma -Tends to be high temperature, low pressure -Baked zones, called aureoles, form around intrusions -We may find the rock hornfels here, which is a hard, nonfoliated rock that forms due to baking. It is a very boring rock -Contact metamorphism is local in scale, and the size of contact metamorphic zones will depend on the volume of material and how much heat is added (are we looking at a dike or a sill, or something huge like a batholith?) -A large batholith may produce an aureole extending for 3-5 km around the intrusion!
Fault Zone Metamorphism
-Deformation occurring along faults -Low pressure and low temperature to high pressure and high temperature
Rock rules
-Developed with sedimentary rocks in mind and tell us about how stratified rocks work and how layers are related to each other -You can use logic for most of them -Often works for igneous and metamorphic rocks -All based off uniformitarianism
How does ductile and brittle deformation relate to whether we see faults or folds?
-Ductile deformation is more elastic, brittle breaks suddenly, so ductile deformation will result in smoother lines or curves while patters in brittle deformation will be jagged, lines will be short -Brittle: joints, faults -Ductile: folds
Law of inclusions
-Each stratum is deposited from fluid upon a solid subjacent surface -Hard (solid) fossils may be incorporated into soft (loose) sediment at this stage -Anything incorporated within another rock bed or layer (pieces of rock or sediment, fossils, etc.) -HAS to be older than the rock that it is stuck within
Seismic waves
-Elastic waves that travel through the Earth -Can also be generated by volcanoes, landslides, nuclear testing, mining explosions, and impacts
Rayleigh waves
-Surface wave -Rolling vertical surface waves -Travel in a backward-rotating, elliptical motion, causing both vertical and horizontal ground movement -Can travel through solid, liquid, and gas -Fourth to arrive -Dangerous -Look like ocean waves
What would it be like to experience the eruption of a shield volcano? what would you expect to see, and what would this volcano look like? How fast would the flow move? Could you outrun it?
-Example: Hawaii, Iceland -Low viscosity mafic magma makes basalt on Earth's surface -Some of the biggest volcanoes on Earth! -What they look like: gentle slopes (3°-5°), -Not terribly impressive in profile -Tectonic settings: hot spots in the ocean crust/lithosphere and divergent boundaries -Example: Mauna Loa -Commonly, lava in Hawaii erupts from fissures in effusive (gentle) flows. -Lava types include A'a' (broken, jagged flows) and Pahoehoe (ropey, smooth looking flows). Pahoehoe flows evolve into A'a' flows as they release volatiles and cool down, increasing their viscosity. This makes the lava flow break apart into pieces -Hazards of shield volcanoes include lava fountains, volcanic ash, lava-caused fires, and lava flows -You can generally outrun this kind of eruption. You just can't stop it
Why does felsic magma produce more explosive eruptions than mafic magma?
-Felsic magma has higher silica content and is therefore more explosive -Explosivity is classified using the VEI: Volcanic Explosivity Index -Classifications are based on comparisons with past eruptions: they refer to specific events
What are some of the characteristics of Iowa that have led to the formation of mollisols soil?
-Formed from our tallgrass prairies -Have dark, humus -Rich surface layers that are mineral rich -Gives Iowa it's very high-quality cropland
What do glaciers do to the underlying land? You should be able to explain why glacial rebound happens, and what this process is.
-Glaciers are HEAVY and cause the crust below then to subside when they are above it -they literally weigh down the crust, depressing it -When glacial ice sheets melt, the crust rebounds: it bounces back up
how fast can glaciers flow
-Glaciers move 25 CM per day up to 30 M per day -Surges are intervals of extremely rapid movement
Hawaii (hotspot)
-Hawaii is at the end of a volcanic island chain created by a hot spot -When you look at the chain of islands, you are seeing the combined motion of both the plate and the hot spot
How much water do we need to survive each day, and how much on average do we use in the United States? Where does most domestic water use go, and where does most water use go in general?
-How much water you need to survive a day: 1.3 gallons, or 5 liters -How much you use: 3794 liters a day. In the United States, we use the most water in the world -Where it goes: cooling stations at different kinds of power plants, irrigation, "public supply"-domestic use. -Where most of your domestic water goes: down the toilet! Please fix the leaks.
What are the characteristics of a transform boundary? (what can it cause)
-Huge stresses can cause portions of the rock to break, resulting in earthquakes -Places where these breaks occur are called faults
Each stratum is laterally continuous
-If you dump sediment into a basin under the influence of gravity, it will spread out until it fills the basin or runs out -Because of this, sedimentary beds are often laterally continuous for 10's of kms -Practically, this lets us make the observation that if rocks look similar even though there is a valley separating them, they probably are indeed the same rocks that formed at the same time and represent the same environment. They have just been separated by erosion
Continent-Continent Convergence
-India and the Eurasian plate produce the Himalayas where they collide -India has been on a path to collide with the Eurasian plate for tens of millions of years - this collision has produced Mt. Everest (the tallest mountain in the world at 8,848 meters) -Mt. Everest is a very deadly mountain -Associated features- very thick crust: Big mountains have deep roots: some of the thickest crust in the world underlies Mt. Everest -Associated features-earthquakes: The fracturing of the Eurasian plate as it converges with the Indian plate produces both crustal shortening (rock is piled up on top of itself here) and abundant earthquakes. In 2015, a Mw 7.8 earthquake (the Gorkha earthquake) devastated this region
Where does Iowa rank in terms of using wind energy in the United States?
-Iowa is the 2nd largest producer of wind energy in the United States, with many large wind farms concentrated in NW Iowa
Characteristics specifically of the San Andreas fault
-Large earthquakes every ~150 years -Different segments behave in different ways -The San Andreas is part of a very complex tectonic setting
Love waves
-Surface waves that shear the ground in a horizontal direction -Horizontal shearing surface waves -Can only travel through solids -Third to arrive -Slide back and forth
Why might one element or combination of elements form different minerals? How does this relate to the geotherm and changing pressure and temperature conditions within the Earth?
-Minerals are environmental fingerprints -If you can identify your mineral, you know the conditions under which the rock it is in formed -Part of what determines which minerals form under particular conditions are minerals' stability fields: -Just like water occurs in different states (solid, liquid, gas) under different temperature and pressure conditions, different minerals will form from the same combination of elements under different pressure and temperature conditions -This means that when we see specific minerals in rocks, they indicate very specific conditions of formation-our environmental indicators! -Pressure and temperature increase predictably with depth in the Earth (the geotherm) -Stability fields tell us that even the same combination of atoms will form different minerals under different temperature and pressure conditions
What are the primary types of fossil fuels, and what are they derived from?
-Most of the energy that we use is derived from fossil fuels (hydrocarbons, or organic material, that may be used as a fuel): These include oil, coal, natural gas, and bitumen from oil sands and oil shale. -coal, petroleum and natural gas -Fossil fuels are found underground, trapped in deposits surrounded by layers of rock
What are PGEs? What are they associated with?
-Ni-Cu-Platinum group elements -example: large layered intrusion in Russia at Noril'sk. Minerals settled to base of magma chamber as it cooled. -We also find PGE (Platinum Group Elements) associated with impact sites, such as at the Sudbury impact site, which melted part of the mantle -Impacts can have many valuable associated deposits due to the formation of melt
Ocean-Continent Convergence
-Oceanic crust subducted -Earthquakes occur at great depths (up to 700 km!) -Subduction zones are the only place on Earth we can get earthquakes at more than 100 km depth (Wadati-Benioff zones) -Trench where plate goes down -Huge mountains! -Volcanism -Addition of water from ocean crust & partial melting of ocean crust -Passes through the continental crust and generates more melt and explosive volcanism -Associated features: high mountains and a deep ocean trench (trench marks the boundary between the two plates)
When did we start using oil widely?
-Oil has been utilized heavily over the past 150 years, with the first oil well drilled in 1847 in Baku, Azerbaijan -The history of oil has multiple phases, with the "Modern" petroleum industry starting around the 1880s -Global discovery and acquisition followed, and then post WWII significant technological advances and subsurface imaging techniques improved our ability to locate this resource -Global oil and gas field development and deep water discoveries occurred in the late 1900s
Why do the highest mountains have the deepest roots?
-Orogenesis builds long, curved mountain belts with thrust faults and folds like chains. Isostasy is when less dense crust floats on denser deformable rocks of the mantle in gravitational balance -Deepest roots indicate longer periods of orogenesis -Isostasy explains how continental crust floats on the mantle, and how thicker crust will produce higher mountains -It works like an Iceburg, 90% of it is underground because of the density difference--> This is needed to support it.
How do earthquakes relate to plate boundaries?
-Our plate boundaries are outlined by earthquakes and interactions at plate boundaries control the distribution of many of the hazards that we worry about no the Earth's surface -
What is "peak production", in terms of petroleum? When do we think peak oil might happen? What is the Hubbert Curve, and what does it show?
-Peak oil refers to the hypothetical point at which global crude oil production will hit its maximum rate, after which production will start to decline -might happen in a range from 2035-2050 Hubburt Curve: -illustrates the idea that oil is a nonrenewable resource and that global oil production either has already or will soon peak -The extraction of oil can have disastrous ecological and human impacts if done incorrectly -Examples: increasing atmospheric CO2, climate change and the Deepwater Horizon oil spill, April 2010
What is currently happening in Antarctica, Greenland and and the Arctic Ocean?
-Rate of sea level rise from 1993-2015: 3.3 mm/yr -This is due to thermal expansion of ocean water as it is heated and the melting of glaciers -Future sea level rise is going to cost us, in terms of more coastal damage -global sea level rise
Regional Metamorphism
-Result of mountain building events -High temperature (550-700°C) and high pressure, occurs at very large scales (continental) -This process produces the bulk of the metamorphic rocks that we observe -As we progress deeper into these collisional systems, we will see more intense metamorphism, which will be reflected in our rock types
What do body waves tell us about the Earth's interior?
-Seismic wave velocity varies as the properties of the material that they are passing through changes (properties include density, elasticity, composition, pressure, and temperature) -When waves pass from one material into a different material, they can be bent (refracted) and may also bounce off of the new material (reflected)
How and why do rounding and mineral composition change with increasing time being transported in a clastic sedimentary system?
-Shape will become more rounded, size will decrease -Mineral comp will change, less stable material will weather out: left w/ quartz
How does elastic rebound theory relate to these two terms? (stress and strain)
-The brittle lithosphere deforms elastically as a result of stress: friction prevents slip along locked zone of fault -When strain exceeds frictional strength, fault slips -Energy is released-earthquake happens-generates permanent offset, heat, seismic waves (radiating energy): rocks bounding fault return to previous shape
Isostacy
-The concept that Earth's crust is floating in gravitational balance upon the material of the mantle -The equilibrium between continental crust and the denser mantle below it
What is longshore drift, and how does it work?
-The main way that waves move sediment around is called longshore drift, which is generated by waves that approach the beach at an angle and drive longshore current development -You may have experienced this phenomenon if you have ever visited the ocean, gone swimming for awhile, and then climbed out half a mile down the coast from where you got in and had to hunt frantically for your beach towel
Ocean-Ocean Convergence (Caribbean)
-The older, colder oceanic lithosphere will subduct. -We see a Wadati-Benioff zone of deep earthquakes (wedge shaped descending earthquake pattern), deep ocean trenches, and curved volcanic island arcs -There can be significant volcanic hazards at these boundaries, as there was on the island of Martinique, where a volcanic eruption in 1902 led to the death of almost the entire population of St. Pierre
Orogenesis
-The process of mountain building -Primarily this process occurs at convergent boundaries
How do subtropical, mid latitude/rain shadow, coastal, continental interior and polar deserts form? Be familiar with the different ways that winds interact with the Earth's surface to produce these different deserts
-The reason that we find deserts in these particular locations (these large desert belts, known as subtropical deserts and steppes) has to do with winds -prevailing wind patterns are the deciding factor of where deserts are
Can a dog predict an earthquake?
-There are reports of weird animal behavior before earthquakes; however, animals always act weird -Right now we don't have a mechanism for why animals could predict them -They can likely sense the arrival of P waves which we cannot feel
Surface waves
-There are rolling vertical surface waves (Rayleigh waves-these look like ocean waves) and horizontal shearing surface waves (Love waves: slide back and forth) -Surface waves are the most destructive waves produced by earthquakes: they cause the worst ground shaking. Love waves are particularly damaging because of their frequency -Surface waves travel the slowest of all seismic waves, and move along the surface of the Earth
Can we cause/make an Earthquake?
-There is strong evidence that wastewater injection into wells for storage can cause earthquakes -These are often minor, but a recent 5.7 in Oklahoma has been linked to wastewater injection -Colorado has also had 4's and 5's associated with wastewater injection after extracting resources from coalbed methane
Elastic strain
-This change in rock shape resulting from stress will be reversed when the fault plane slips (rocks will return to original shape) -This is exactly like what happens with a rubber band when you stretch it out: when you let go, it goes back to its original shape
Avalanches
-VERY FAST motion -example: in a snow avalanche, air-snow mixture is denser than air and runs along the ground. This moves like a strong and viscous wind
How VISCOSITY AND COOLING SPEED relates to crystal lattices and intrusive vs. extrusive environments
-Viscosity of magma and lava determines how hard it is for atoms to migrate and form bigger crystals -Hot rocks are less viscous than cold rocks (atoms have an easier time getting around) Wet rocks are less viscous than dry rocks -You can think of atoms as trying to build large crystal lattices- if viscosity stays low for longer, they get more of a chance to do this, which will be reflected in the size of crystals in your rock -The end result of viscosity (and what it tells us about the time minerals had to get organized) is that we can use crystal size to infer where and how rocks formed
What are the characteristics of a divergent boundary? (what can it cause)
-Volcanoes (such as the dormant Mt. Kilimanjaro, which sits at 5750 meters or 19,000 feet and is snow capped even though it is 3° from the equator, and Nyamuragira) -A submarine mountain range such as the Mid-Atlantic Ridge -Shallow earthquake activity -Creation of new seafloor and a widening ocean basin
How does stress differ from strain?
Stress: the force per unit area exerted on an object Strain: the resulting deformation
Is any part of the US at risk for desertification? If so, where?
-Water scarcity is a major issue: we observe both physical water scarcity and economic water scarcity -This is an issue that can drive desertification, and that we will have to come to grips with over the next few decades -Water resources are critical to survival in desert regions -Pumping groundwater lowers the water table at a rate faster than it is replenished. Watch the video on the Wilcox Basin -Quitaboquito Springs in the Organ Pipe National Monument, Arizona, is a classic example of a water resource critical to survival in the desert
Unconformities
-We know that we are MISSING TIME -We either have an erosional surface, or a surface of non-deposition -Gaps in rock sequences
How can weathering cause secondary enrichment of ore deposits?
-Weathering can result in secondary enrichment of ore deposits: concentration of scattered, minor amounts of metals through weathering processes -Two types: 1) Chemical weathering and water percolation remove undesirable elements from decomposing rock, leaving behind higher concentrations of desired elements 2) Desirable elements found near surface are carried to lower zones, where they are concentrated
What is the main erosional agent in deserts? Do we observe more physical or chemical weathering in deserts?
-Weathering in arid climates: in arid climates, we observe (the same/different) processes compared to those that operate in humid regions, with the following outcomes: -Most weathered debris in deserts consists of unaltered rock and mineral fragments from mechanical weathering (low humidity results in very little chemical weathering). What we get: clay, thin soils, oxidized minerals -Our most powerful erosional force in deserts: water -Deserts are characterized by dry channels (beds of ephemeral streams that only contain water during heavy rainfall)
How are floods defined?
-When discharge exceeds a set point, or when stream stage reaches flood stage, a river floods -your river leaves its channel -Levees often help contain the channel and can be natural or artificial -once the channel is breached, the stream spreads out across its floodplain and deposits fine sediment on the floodplain after dumping coarse sediment next to the stream channel (levees are built of this coarse sediment)
Impact Metamorphism
-When meteorites hit the Earth (at speeds of up to 45,000 mph!!!), they will produce impact features due to the intense energy of impact -Carbon can be changed to diamond in these impacts, and we see planar deformation features in minerals where the mineral structure slipped so fast that we got frictional melting -We also see shocked quartz and tektities (silica-rich glasses formed by complete melting and then cooling, often while flying through the atmosphere) forming in these situations
Disconformity
-Wrong ages -We skip parts of the geologic time scale due to either a lack of deposition or deposition and then removal of material through erosion -We are missing time and our rock record is discontinuous
Angular unconformity
-Wrong angles -These are nice and obvious -James hutton first recognized angular unconformities at Siccar Point, Scotland -Hutton was a great observer of erosion and deposition (seriously, he liked to watch rocks erode), and correctly recognized that to form rocks like those observed at Siccar Point you needed a LOT of time -He has one of the greatest quotes in geology ("...no vestige of a beginning, no prospect of an end.") -He recognized the idea of uniformitarianism
Yellowstone, the Supervolcano (hot spot)
-Yellowstone's various hydrothermal features are a result of being perched above this magma chamber -Historically produced very large eruptions -You can track the movement of the North American plate by looking at the track of large calderas (a kind of volcanic feature) formed by this hotspot
Cross cutting relationships
-Younger features will cut across features that formed before them -This includes faults, erosional surfaces, dikes, veins, etc.
oxbow lake
-a crescent-shaped lake (often temporary) that is formed when a meander of a river is cut off from the main channel -abandoned loop
How do diamonds reach the surface?
-a form of carbon created at great depths, under high pressure -Diamonds reach the surface in conduits within ultramafic rocks called kimberlite pipes -We find kimberlite associated diamonds in many areas throughout the world -These represent material coming from the base of the lithosphere, and reaching the crust at high speeds
What is a glacier, and what cycles are they a part of? How much of the Earth do they cover? Is glacier ice a rock?
-a glacier is a thick mass of ice originating on land that forms from the accumulation, compaction and recrystallization of snow -are part of both the HYDROLOGIC cycle and the ROCK cycle -they cover nearly 10% of Earth's land surface! -Glacier ice is a mono-mineralic rock, made up of the mineral ice, the crystalline form of H2O -Glaciers are significant erosional forces
ore
-a rock that contains useful metallic minerals in sufficient quantities to make it valuable for mining -This is also used to refer to some nonmetallic minerals, such as fluorite and sulfur
Permeability
-ability of rock or soil to allow water to flow through it -a measure of connectivity-how easy is it to transmit fluids?
The zone of aeration
-above the water table -Air and water both exist in pore spaces
What is zachos curve, and how far back in time does it extend?
-an important and relatively high precision record of climate change that lets us investigate not only the magnitude and rate of past changes, but also impacts on the flora and fauna -a record of the last ~65 million years of climate change
what is the IPCC (Intergovernmental Panel on Climate Change) and what is their job?
-an international group that assesses and disseminates the science associated with climate change -to provide the world with a clear, specific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts
meander scar
-an isolated meander that is not filled with water -dried up oxbow lake
ground moraine
-an uneven blanket of till that is deposited beneath a glacier and exposed as the ice front retreats -This leaves a hummocky, irregular land surface -we design golf courses to look like this (so you could practice identifying a lot of glacier features by identifying the shapes on golf courses)
What is a biofuel? What are some examples of different biofuels? What are some disadvantages to using biofuels in your engine?
-are fuels derived from biomass (recently living organisms OR their metabolic products) -Pros: biofuels are renewable -Cons: combustion of biofuels produces greenhouse gasses, including CO2 EX: bioethanol
Oil traps
-are geologic environments that allow economically significant amounts of oil and natural gas to accumulate underground -To form these, a cap rock (impermeable) is required and must be adjacent to a porous, permeable, reservoir rock
BACKSHORE
-area between high-tide shoreline and farther back -This area is usually dry, but is impacted by wave erosion during unusually high tides and by storm waves
FORESHORE
-area between low-tide low-water line and high-tide high-water line (most active area in terms of waves, gets wet every day) -his area is acted upon almost constantly by waves
what defines drainage basins edges?
-by topographic highs that create drainage divides -the edge of a drainage basin is characterized by the highest points of land around the river, this is known as the watershed. The point at which a river starts is called its source. As the river continues to flow downstream it may be joined by smaller rivers called tributaries
Details on the types of material that can be involved in mass wasting events
-consolidated material/rocks: descending material began as solid rock -debris/earth (DIRT!): descending material is unconsolidated
changes in configuration of continents
-continent positions are not at all stable through time -our current ocean circulation is driven by winds, differences in density of different water masses that are governed by salinity content and temperature, and the edges of continents, which direct currents
Flow
-continuous downslope movement of water-saturated material (rock and/or regolith) that moves like a viscous fluid -the type of flow is classified based on the velocity at which this occurs -includes earth flows, debris flows, and avalanches -unconsolidated
How much of Earth's surface was covered by glaciers during the Pleistocene (and when was the Pleistocene)?
-covered 30% of the ground surface of the Earth -Glaciers drive significant sea level change -during the ice ages 2.58 million years ago
What is the Coriolis Effect, and what part of the ocean does it impact?
-describes the deflection of moving objects due to Earth's rotation -can be difficult to explain and to understand at a first pass but makes a lot of sense once you wrap your head around it I expect you to remember is the large-scale patterns that it generates in terms of wind and ocean currents.
MORAINES
-erosional landforms -are layers or ridges of stony debris (till) deposited along the margins of or beneath a glacier -till is poorly sorted deposit!
How do we get oil out of shales? Why do we need sand to do this?
-fine-grained, dark sedimentary rocks with enough organic material to yield oil or combustible gas upon distillation -Pros: huge amounts of untapped oil are contained in sales -Cons: currently, technology for extraction is very expensive and there are huge environmental risks if this is done improperly -How we get this out: hydraulic fracturing. Deep wells are drilled, and water is pumped down them at very high pressures. Water forces fractures to form, proppant in the water holds fractures open, allowing oil to flow out
Under what conditions will a glacier form?
-glaciers can only form in areas where more snow is added ACCUMULATION then melts or evaporates (wastage) -A glacier is a balance between these two factors, with accumulation at the head and wastage at the foot -Once glaciers form and ice accumulates, they flow downslope under the influence of gravity
changes in albedo
-has a significant effect on the equilibrium temperature of the Earth as it changes how much solar energy is reflected by the Earth as opposed to how much is absorbed -surfaces that are more reflective have (higher/lower) albedo
What is desertification, and how are we making this process more likely?
-in many regions of the world, we are having issues with advancing deserts -This process is driven by climate change, overgrazing, and also drought
Polar deserts
-it is cold in the polar regions, so there is very little moisture in the air -the Polar atmospheric cells tend to isolate the cold air at the poles and it gets even drier
AQUICLUDES/AQUITARDS
-layers that do not permit water movement -Great aquicludes include: shale layers, clay
What are the characteristics of a convergent boundary? (what can it cause)
-leading to the formation of volcanoes -the lifting of mountain ranges -the creation of deep oceanic trenches
Creep
-low, continuous movement of material down slope -this is often related to freeze -thaw cycles and makes tilted trees! -tilted fences, breaks in retaining walls, and cracks in roads are all signs that creep is occurring -unconsolidated
Landslides
-material fails and initially moves along a well-defined plane (the landslide portion of the event), breaking up into a chaotic jumble as it continues downhill (the debris flow portion of the event) -unconsolidated -can turn into debris flows during single events due to addition of water and/or loss of sediment cohesion -they can also just stay landslides, but usually the materials break up
What are oil sands, and what are some of the pros and cons of using them as a fuel source? Where do we find them, worldwide?
-mixtures of clay and sand combined with water and bitumen (viscous, degraded form of oil) -Pros: Oil sand deposits exist in substantial quantities throughout the world -Cons: extraction is both difficult and expensive and can be very environmentally damaging -How some deposits formed (plate tectonic setting): Ocean-Continent convergence -Canada has extensive oil sand deposits associated also with oil fields and gas fields; all part of a foreland fold and thrust belt -Heavy and extra-heavy oil basins are widespread worldwide (127 basins, according to USGS)
bioethanol
-most common type of biofuel -It is obtained by fermentation, distillation, dehydration and denaturing of starches or sugars that are found in many crops -Pros: can be blended with petroleum gasoline! US blends of gasoline typically contain 5-20% ethanol -Cons: some engines are not compatible with ethanol. You can get corrosion and deposits when you use this in these engines
What do phytoplankton need to bloom, and how does this relate to upwelling?
-need light to photosynthesize -One potential avenue for mitigating climate change is to artificially cause these blooms: scientists think we can dump iron into the oceans where it is limiting, and drive blooms -this might not actually work, though, and also may have unintended consequences -upwelling can drive phytoplankton to bloom
Nonconformity
-not the right kinds -How did those igneous or metamorphic rocks get in here??? -Sedimentary rocks overlie eroded igneous or metamorphic rocks
Debris flows
-observe the moderate to rapid movement of water-saturated, primarily coarse -grained unconsolidated materials downslope -these events occur most commonly in semi-arid mountainous regions, and are frequently confined to existing stream channels or canyons -often triggered by periods of heavy rains-lahars are a special kind of debris flow that occurs on volcanic slopes
Stratigraphic traps
-occur as a result of original sedimentary structures, where reservoir rocks pinch out (thin to point of disappearance) -An example of this might be sandstones that had originally formed as sand bars, adjacent to rivers
Solifluction
-occurs when only the upper most layer of permafrost melts in high elevation regions in the summer -ground flows downhill in overlapping sheets, supported by a soggy base that rests on top of unthawed solid ground a few meters down -unconsolidated
levee
-often help contain the channel and can be natural or artificial -an embankment built to prevent the overflow of a river
What are oil and gas made of?
-oil and natural gas are formed from organic matter from dead plants and animals -These hydrocarbons take millions of years to form under very specific pressure and temperature conditions
unconfined aquifer
-open to incoming groundwater from the top -much more susceptible to pollution
large-scale patterns that the Coriolis Effect generates in terms of wind and ocean currents
-our winds are deflected and they push ocean surface currents with them -Pilots actually have to work the Coriolis effect into long flight paths, or they would end up in the wrong place! -these winds drive our large scale patterns in surface ocean currents -wind patterns are also important for upwelling: when strong winds blow seasonally along coasts, water can either be pushed against the coast or pulled away from the coast -when it is pulled away, upwelling of cold, nutrient rich water can lead to seasonally productive coasts -we see this in California, as well as in other places
How do streams interact with the water table in deserts?
-permanent rivers that cross arid regions typically originate outside of deserts in the mountains -Water table is usually very deep, and most streams are losing (between infiltration and evaporation, streams are rapidly depleted)
what is a hydrograph?
-plot the flow of a stream vs. time -we see a lag in timing of maximum flow as water that has infiltrated into the ground and water that is running as sheet flow over the ground surface makes its way into a stream and down through a drainage basin -only 1-5% of rain falls directly into a stream during a precipitation event-the rest of the rain will slowly find its way there
milankovitch cycles
-predictable variations in earth's position in space relative to the Sun that affect climate -changes in the shape earth's orbit and tilt that cause glacial periods and interglacial periods
What do tides result from (what two bodies exert gravitational pulls on the Earth and its water, and which is stronger)?
-result from the interaction of the moon and the sun, which exert gravitational pulls on the Earth and its water (the moon exerts about twice the pull that the sun does) -Because of this gravitational force, both the Earth and the oceans are pulled towards the moon, creating a bulge of water and earth on the side of the Earth facing the moon. On the side of the Earth directly opposite from the moon, the movement of the Earth towards the moon and also reduced gravitational attraction of the ocean water creates another bulge. The sun has a similar but smaller effect. As the Earth rotates, it moves underneath these bulges-this is what gives us our tides!
Details on the types of movement that we may observe in mass wasting events
-rock fall -rock slide -flow -landslides -creep
confined aquifer
-sandwiched between two aquicludes -Confined aquifers tend to have higher water quality, since there are fewer places for contaminants to enter -You can also have perched aquifers, sitting up on aquicludes above the regional water table
jetties/groins
-shore-perpendicular structures that are used to protect harbors or accumulate sand -sand accumulates up current, and these structures do successfully prevent the transport of sand down the beach -Problem: if you aren't moving sand down the beach, you get really bad erosion anywhere that lacks a jetty or groin
What are gas hydrates, and where do we find them? What is the big downside of potentially utilizing them as a fuel source?
-solid forms of water that contain methane within ice-like crystals -These exist at low temperatures and high pressures -We find deposits occurring both naturally on the ocean floor and also in permafrost. -Pros: methane is a potential energy source, and we have a lot of it accessible in hydrates -Cons: methane is a much more potent greenhouse gas than carbon dioxide, so if we use them we contribute to climate change
losing stream
-streams in arid climates are frequently losing streams -water seeps out of them and downwards into the water table
gaining stream
-streams in humid climates tend to gain water -the groundwater table is high enough that it releases water into the streams
Things we can measure: GRADIENT
-tells us how fast a stream is dropping -it is calculated by dividing the elevation change along a portion of the stream by the distance measured ALONG the channel -gradient changes as we move downstream: streams have steep headwaters, and decrease in steepness towards base level) -A delta forms where a stream enters a standing body of water, slows down, and drops its sediment load
how does combustion generate carbon dioxide?
-the carbon from the fuel combines with oxygen from the air to produce carbon dioxide -CO2 is added to the atmosphere through combustion, which increases the growth of forests -increased plant biomass results in increased uptake of atmospheric CO2
What is the name of the Earth's ocean circulation pattern, and what two factors that impact density drive it?
-the combination of salinity, temperatures, and surface currents drive's the Earth's thermohaline circulation system, which powerfully impacts climate -our global patterns of temperature, salinity, and surface currents control Earth's thermohaline circulation system (heat and salt) -This circulation pattern is critical: it oxygenates the deep ocean and also moves water all around the globe in slow and poorly understood movements -This is a huge driver of global climate
What does the water table look like-how does it relate to topography?
-the land surface -The water table is controlled primarily by climate and its depth varies seasonably. In arid regions, it may be 10s to hundreds of meters below the surface, whereas in humid areas it may be centimeters below the surface and may be intersected by the surface of lakes and streams. -The water table mimics the land surface, and water flows downslope -Hydraulic head is the energy available to drive groundwater flow, which depends on the amount of overlying water within the saturated zone -Streams in humid climates tend to gain water: the groundwater table is high enough that it releases water into the streams. Ponds and streams in these environments may intersect the water table (it sits at the surface) -Streams in arid climates are frequently losing streams: water seeps out of them and downwards into the water table, which may be tens to hundreds of meters down
Base level
-the lowest level that a stream can erode to -sea level is ULTIMATE base level, though there are a few streams that erode to points lower than this in the world -Dams create artificial base levels, and dams do a few things: they trap sediment behind the dam and starve downstream areas of sediment
What are mineral resources?
-the naturally occurring variety of useful and essential minerals from Earth's crust, ultimately available commercially according to value. -Examples: iron ore, lead, tin, zinc, copper, mercury, bauxite
Continental Interior deserts
-these form inland on large land masses (example: Australia) -As wind moves inland, it loses moisture through precipitation -Basically, there's just no precipitation left to reach the interior of these continents
What is a placer deposit? What are the physical characteristics of minerals associated with these types of deposits?
-these form when heavy minerals are mechanically concentrated by currents -This is most common in streams and flowing water, and tends to happen with heavy and durable minerals -This is particularly a common way to find gold, as well as tin, platinum, and diamonds -Extracting placer deposits can greatly disturb the surface, and may require reclamation/remediation
How do deep water waves move water (what is the shape of water orbits, and how deep, relative to wavelength, are water particles moved)?
-water particles move in circular orbits -Do particles progress?: NO -This is how waves behave when they are in water that is deeper than half their wavelength -they can't "feel" the bottom and do not disturb sediment
How has resource use changed in the last 100 years (both in terms of total amount used, and in terms of what we are using to produce energy)?
-we are using a lot more energy than we did a century ago, and the kinds of resources that we exploit have changed (we see shifts from using predominantly wood to coal to petroleum, with other energy resources also being utilized) -At the same time, we have seen dramatic population growth: in 1800, the world population was 1 billion -It is currently above 7.8 billion -This means we're going to use a lot more stuff -36% petroleum, 31% natural gas, 13% coal, 8% nuclear power, and 11% renewables Renewables: 45% biomass, 22% wind, 2% geothermal, 23% hydroelectric, 8% solar
What is a desert (how do we define arid climates)?
-we define these dry climate zones as areas where yearly precipitation is not as great as the loss of water by evaporation -Desert: extremely arid, driest of the dry climate zones -Steppe: semi-arid marginal zone that borders deserts
How do waves change as they move into shallow water (what happens to their orbits)?
-when waves reach a water depth that is half their wavelength or less, they start to "feel" the bottom -orbits become elliptical and the wave is frictionally slowed and leans forward, getting taller -At 1/20th wavelength, the waves break -Whether or not waves feel the bottom determines how and if they interact with sediment -Close to shore and along the shore on the continental shelf, areas will experience wave action frequently -Farther out on the continental shelf and in the deep ocean, some areas will never experience wave action
What are our 3 different ways of generating melt and what plate tectonic settings are they associated with?
1) Add HEAT (thermal melting): -Remember the geotherm, which shows us how temperature and pressure increase with depth into the Earth -At convergent boundaries, we can push one plate down to great depths, where it will heat up and melt 2) Decrease pressure (decompression melting): -Where plates pull apart from each other at divergent boundaries, solid mantle material moves upwards into a lower pressure environment and melts due to decompression 3) Add WATER (fluid-induced or 'flux' melting) -At convergent boundaries, we can also force water-rich minerals and sediment down into the Earth -Water lowers the melting point of rocks, so this process can generate flux melting in the surrounding material
How have we estimated the age of the Earth?
1) Age of METEORITES 2) Dated moon rocks (Apollo astronauts collected 392 kg of moon rocks!): 4.46 Ga
What are our two kinds of stream morphologies, and how do they differ?
1) BRAIDED STREAMS: -These streams have multiple channels separated by islands and bars of sediment -They have extremely heavy sediment loads, and frequently variable water levels -this prevents the establishment of plants on banks, which would otherwise help stabilize these systems -We find these coming out of steep, mountainous areas and associated with glacier. 2) MEANDERING RIVERS/STREAMS: These have a single channel that curves back and forth
What are our three different kinds of plate boundaries and two different kinds of crusts? How do we classify the layers of the Earth (two methods)?
1) CONVERGENT (plates collide) 2) Divergent (plates move apart) 3) Transform (plates slide past each other) The type of crust can be: 1) Oceanic 2) Continental How do we classify: Earth is layered, and that you can define its layers based on either chemistry (what they're made of) or strength (are they squishy? Are they brittle?). The outer hard shell of the Earth- the lithosphere- is broken into plates that interact at plate boundaries
What do you need to capture oil and natural gas?
1) Cap rock is punctured by drill 2) Oil and gas, under pressure from overlying rock, migrate from pore spaces of reservoir rock into drill hole 3) Oil and gas are either pumped out or may rise (if under sufficient pressure) without pumping to surface 4) Separators sort oil and gas into separate storage tanks
What are some environmental consequences of using coal to generate power?
1) Coal takes millions of years to form, so it is non-renewable (once we use it up, it's gone) 2) Mining can be environmentally detrimental 3) Coal combustion leads to significant air pollution
How we calculate stream flow:
1) Discharge: -cross section (depth * width) -how fast water is moving gives us discharge in meters per second -This is a measure of how much water is flowing past a point on the stream at any moment in time 2) Stream stages: -these measure stream HEIGHT against a reference point -When height gets high enough, we enter a flood stage
What were the 4 early observations that scientists made, that suggested that continents hadn't always been fixed in their current positions?
1) Faunal distributions: extinct organisms (fossil fauna) have distributions across unconnected continents. Scientists used to explain this as resulting from land bridges that rose up out of the ocean and then sank back into it, but you need a LOT of mysterious land bridges for this to work 2) Fit of edges of continents: it looks like a lot of the continent edges would fit pretty nicely with each other, if we could just rearrange them 3) Matches between rock types/mountain belts: some mountain belts seem to be split by oceans, and are currently on different continents 4) Past Glaciations: a. Glacial deposits (and sense of motion indicators) do not make sense given the current position of continents b. If continents are fixed: glaciers would have to have formed at equators and moved north, and would have had to flow onto land and uphill from the sea c. If we reposition the continents into a supercontinent (perhaps the supercontinent Pangea), the glaciers can behave in a "normal" fashion (form at high latitudes, flow from inland outwards towards the sea)
What were the post-WWII observations that provided further support for the theory that continents hadn't always been fixed in their current positions?
1) Ocean floor is youngest at ridges and increases in age away from them 2) Sediment thickness is in general very thin, and only gets thick at very edges of continents 3) Oldest ocean floor is only 200 MYA (MYA = million years old)! So we are missing more than 95% of the Earth's 4.5 billion year record! 4) GPS: network of 30 satellites with ground-based receivers. These very precisely track plate motion (if you have a Garmin in your car, you know that they're really good at locating stuff on the surface of the Earth) 5) InSAR (Interferometric Synthetic Aperture Radar) is a completely satellite based method for measuring ground movement. In contrast, GPS relies on earth-based equipment as well as satellites. InSAR satellites operate using a similar principle to sonar-they bounce signals off of Earth's surface: We can compare passes and their data from different times to see earthquake (and volcano, and etc.) related ground displacement
What streams do:
1) They move water in laminar or turbulent flows 2) They weather the material (bedrock or sediment) that they flow over 3) They transport sediment downstream
Our final igneous rock type is determined by:
1) Type of material that was melted (source), and addition/deletion of different components 2) Way the material solidified (rate of cooling, related to whether rock is intrusive vs. extrusive) -When we are thinking about the type, or source, of material for an igneous rock, you want to consider whether we melted oceanic or continental crust or the mantle; whether we see fractional crystallization; whether we are assimilating other materials
What are the two different types of glaciers?
1) VALLEY: -(Alpine) glacier: glacier confined to flow down a mountain valley, usually in a former stream valley from an accumulation center at the head of the valley -Examples: Bucher Glacier, Alaska and Franz Joseph Glacier, New Zealand 2) ICESHEET: -very large, thick mass of glacial ice flowing outward in all directions from one or more accumulation centers, often called continental ice sheets because they exist on such large scales -This is what Greenland and Antarctica are covered by
4 steps to become a fossil
1) be ROBUST and HAVE HARD PARTS (teeth, bones, shells, pollen) 2) be abundant (AND LIVE A LONG TIME!) 3) get buried quickly (be marine, or at least fall in a lake) 4) get buried somewhere anoxic to avoid bacterial decay (deep marine)
What are the 5 large-scale drivers of global climate change?
1) changes in incoming solar insolation 2) changes in configuration of continents 3) changes in albedo 4) changes in atmospheric composition 5) milankovitch cycles
What are the 6 climate proxies?
1) glacial extent 2) leaf shape 3) dendrochronology 4) pack rat middens 5) stable isotopes 6) ice cores
What are the factors that impact the angle of repose?
1) grain size (finer=shallower slope) 2) angularity of particles (more angular = steeper slope) 3) water content (this varies-a little water makes grains "sticky" but a lot of water floats grains and results in collapse) 4) friction of surface beneath material: high friction surfaces will increase the angle of repose, because they will reduce the tendency of particles at the base to slip -structure is also important: structure influences stability. We see this with highways where we cut into structures that dip towards roadways-this is a good recipe for slope failure
How can we prevent future slope failure?
1) hazard mapping and zoning restrictions 2) revegetation (holds slopes together) 3) regrading: stabilize slopes (get closer to angle of repose) 4) reinforcement (rock bolts, rock nets) 5) improved drainage
What factors do we use to classify mass wasting events?
1) how does material move: fall, slide, flow, or creep 2) what type of material moves: is it solid rock or unconsolidated dirt, loose rocks, sediments, and other materials? 3) what is the rate of movement: fast or slow
What are the three primary energy sources today?
1) nuclear energy 2) fossil energy -- like oil, coal and natural gas 3) renewable sources -- like wind, solar, geothermal and hydropower.
What are the two different ways by which magmatic segregation can concentrate minerals?
1) seperation of heavy minerals that crystallize early 2) Enrichment of rare elements in remaining melt
6 characteristics of a good index fossil
1) short ranging (they don't persist for a long time as a species, so you can break time into small intervals) 2) facies independent: they exist in a lot of different habitats so you can find them all over the place 3) distributed globally, so you can again match things everywhere 4) easy to identify 5) easy to preserve (they persist in the geologic record) 6) common-you can find LOTS of them.
how do we make glacial ice (4 steps)?
1) snowflakes become smaller, thicker, and more spherical 2) air is forced out of pore spaces-compaction 3) snowflakes recrystallize into denser masses of small grains called *firn 4) under pressure, firn fuses into solid mass of interlocking ice crystals (glacial ice).
What 3 things do index fossils allow us to do?
1) to more finely divide time intervals in areas where all the rocks look the same 2) to correlate similar looking rock types in very different areas 3) to correlate very different rock types in very different areas
what are the 5 major greenhouse gases?
1) water vapor 2) carbon dioxide 3) methane 4) nitrous oxide 5) fluorinated gases
What factors interact to determine the size of waves?
1. Wind speed (how hard is the wind blowing?) 2. Fetch: over what distance is the wind blowing? 3. Duration - how long is the wind blowing for? 4. Water depth is also important (though only for shallow water waves)
what are zones of discharge and recharge?
1. Zone of recharge: we add groundwater 2. Zone of discharge: groundwater leaves the system
What 3 general types of fossils exist and what order do they appear in the fossil record ?
1. chemical fossils 2. trace fossils 3. body fossils
What kind of deposits do we find copper in, in Utah?
12 million tons of copper extracted since 1904! Where copper occurs: in copper bearing minerals (bornite and chalcopyrite) in veins which cut across hydrothermally altered granite. Size of pit: 2.75 miles wide, 4,000 ft. deep. Located 20 miles outside of Salt Lake City
Convergent Boundary
2 plates come towards each other: -makes the lithosphere in the area SHORTER -we recycle old lithosphere in zones called subduction zones -these boundaries are destructive -in the process of subduction, one plate dives under another plate, going down into the mantle where it eventually melts
Divergent Boundary
2 plates move away from each other: -Boundaries are also called "creative", since new crust is generated here -Mid Atlantic Ridge (oceanic) -African Rift Valley (continental, becoming oceanic)
How old is the oldest ocean crust?
200 million years old
What is the current average global sea level rise? Can this increase?
3.3 mm/yr yes
What is the difference between global sea level rise and local sea level rise?
A rise in global sea level occurs due to the warming of the ocean and the addition of fresh water into the ocean basins from melting ice on land. Local sea level, known as relative sea level change, is affected by global sea level fluctuations, changes in land elevation, winds, and ocean circulation
what percentage of people in the United States use groundwater daily?
About 44% of people in the United States use groundwater daily. Public water supplies get 33% of their water from groundwater, and domestic supplies get ~98% of their supply from groundwater
What kinds of rocks do we find on Mars? What else do we find evidence of?
And many geologists have turned their attention to other planets like Mars, where we are now finding SEDIMENTARY rocks and evidence of running water.
What is the limestone that makes up much of Iowa made of?
Animals
Left lateral strike slip fault
As you face the fault, the opposite side of the fault moves to the left
Right lateral strike slip fault
As you face the fault, the opposite side of the fault moves to the right
What kinds of deposits are associated with divergent margins?
Associated deposits: -submarine hydrothermal systems (smokers) -Here, minerals like copper, lead, zinc, silver and gold may precipitate out of cooling material. -Back-arc spreading centers associated with convergent margins may also have associated ores forming by similar mechanisms
Why drives atmospheric convection and forms the 3 major circulation cells in the northern and southern hemispheres?
Atmospheric convection is caused by variation in air density: cool, dry air sinks and warm, moist air rises. The atmosphere is divided into 3 major circulation cells (Polar, Ferrel, Hadley). The jet streams that form between the circulation cells are important in generating and distributing weather systems across the planet: latitudinal shifts in the jet streams result in changing weather and if long term, climate.
What are the two processes by which glaciers flow? How fast can they move?
BASAL SLIIP: -ice mass slides over the surface below -We think most glaciers move this way. PLASTIC FLOW: -ice moves within the glacier, behaving like a plastic material (this happens deep within glacier: >50 meters of ice overlying) -this is a kind of ductile deformation Glacial surface features ABOVE this include the zone of fracture, where the upper, brittle part of the glacier causes crevasses to form. *Crevasses are deep cracks in the brittle surface of a glacier
How do we work out a glacial budget (what happens if we have more or less accumulation relative to loss)?
Balance between accumulation and melting/ablation: Advance:= accumulation exceeds loss; Retreat:= loss exceeds accumulation; Balance: = accumulation roughly equivalent to loss (glacial front is stationary)
Oceanic divergence
Best example of this boundary type is the Mid Atlantic Ridge or East Pacific Rise: Crust pulls apart, asthenosphere rises and melts, and we get new crust. Mid ocean ridges are massive underwater volcanic chains. Spreading rates vary from 1-20 cm/year
Recognize the different types of nonmetallic mineral resources.
Building materials: -Natural aggregates (crushed stone, sand, gravel) -Gypsum (used t make plaster and wallboard) -Clay (used to make tile, bricks, cement). Different kinds of clay exist: kaolinite, illite, bentonite. These are also used to manufacture paper, china and ceramics, and different kinds of food. Industrial minerals: -Fertilizers (nitrate, phosphate, potassium compounds) -Sulfur (sulfuric acid is used to manufacture phosphate fertilizers) -Salt (used in chemical industry, for softening residential water, for keeping streets ice free in the winter)
What is the best observational data set that demonstrates increasing atmospheric CO2 levels over the past 60 years?
Carbon dioxide concentrations are rising mostly because of the fossil fuels that people are burning for energy.
Oxidation
Chemical weathering process in which a substance combines with oxygen, as when iron oxidizes, forming rust
Dissolution
Chemical weathering process where minerals are dissolved in fluid and can be transported as ions
Hydrolysis
Chemical weathering process where water reacts with carbon dioxide and splits a molecule
What factors resist mass wasting on a slope?
Cohesion, bonds, surface tension, and friction
Types of Stress
Compression: MATERIAL IS SQUEEZED TOGETHER Tension: MATERIAL IS PULLED APART Shear: TWO SIDES OF MATERIAL ARE PUSHED PAST EACH OTHER
Continent-ocean subduction zone
Continental arc from subducting plate producing partial melt
What kind of environment do limestones form in?
Coral reefs, warm water
How does ductile deformation differ from brittle formation?
DUCTILE or plastic deformation: rocks flow, often generating folds BRITTLE DEFORMATION: rocks break suddenly and we may see movement along faults (we produce fractures this way)
What percentage of the Earth's surface is covered by deserts and steppes?
Deserts and steppes cover 30% of the land surface on Earth (42 million square kilometers)
What are the differences between diamonds and graphite (pencil lead)?
Diamonds: -Hardness: 10 -Uses: industrial cutting, ornamentation -Structure: covalent bonds in all directions -Super deep igneous rocks -Forms at extreme pressure and temperature, at depth -From Greek adamant: invincible Graphite: -Hardness: 1-2 -Uses: lubricant, pencil lead -Structure: bonded sheets held together by van der Waals forces -Often metamorphic, sometimes igneous -Usually result of metamorphism of limestones & coals containing organics -From Greek graphein: to write
For what igneous rocks will original horizontality NOT apply?
Dikes and intrusions
For what igneous rocks will superposition NOT apply?
Dikes, Sills, and Intrusions
How viscosity and cooling speed relates to CRYSTAL LATTICES and INTRUSIVE VS EXTRUSIVE ENVIRONMENTS (part 2)
EXTRUSIVE ENVIRONMENTS: -EX: Volcanones -Magma can reach surface very rapidly (at which point we call it lava) -Atoms don't have a lot of time to organize, because viscosity increases as rocks cool down INTRUSIVE ENVIRONMENTS: -Ex. Plutons, dikes, sills (magma cooled and formed a rock without reaching the surface) -Atoms have more time to move around and get organized, so we get bigger crystals
Mafic vs. Felsic
Felsic: (continental crust), Feldspar (orthoclase, plagioclase), Si-rich, low melting point, light, high viscosity (stiff like ice), high gas/volatile content Made form EXPLOSIVE (strato) volcanos - steep slope, fast moving lava Mafic: (ocean crust), Mg-Fe rich, high melting point, dark, dense, low viscosity (runny like water) Made for EFFUSIVE (shield) volcanos - low incline, slow moving lava
What is a recurrence interval, how is it calculated, and could Colorado get another 100+ year flood this year?
Flood recurrence interval (R) R=(N+1)/m R=recurrence interval N=number of years on record M=rank of flood relative to highest annual flow for the time span we have records for -With every new largest flood, the recurrence interval of the next largest event drops by approximately half Colorado: yes
With increasing metamorphic grade, how would you expect crystal size and foliation to change?
Foliation would increase and grain size increases as well
Stress
Force applied to a given area
Evaporites
Form when water evaporates and leaves minerals behind
Rock fall
Free-falling rocks (very destructive) consolidated
What is uniformitarianism, and why is it useful?
Geology as a whole lets us use the process of UNIFORMITARIANISM ("The present is the key to the past") to make sense of what has happened by applying the lessons that we learn from studying rocks today. We can then use relative and numerical dating to put order to Earth's 4.56 billion years of history.
What was Glacial Lake Missoula, and what happened there?
Glaciers can also be associated with violent flooding events: Glacial Lake Missoula had frequent catastrophic flooding events, where water rushed from this lake out towards the Columbia River. These megaflood events shaped many land surfaces in the west
What drives mass wasting events, in one word?
Gravity
To release important nutrient elements into the environment and to make sediment, which gives us our sedimentary rocks
How do weathering and erosion work together?
Which igneous rock textures are associated with intrusive vs. extrusive environments?
INSTRUSIVE ENVIRONMENTS: -Phaneritic textures (coarse grained-you can see individual crystals, like in granite, diorite, and gabbro) to pegmatitic textures (extremely coarse grained, with grains on average larger than 1 cm) EXTRUSIVE ENVIRONMENTS: -Rocks are fine grained/aphanitic (like andesite, rhyolite, or basalt), glassy (like obsidian), or vesicular and aphanitic from the escape of volatiles (bubbly, like pumice or scoria). We may also see pyroclastic or fragmental textures-these are hot material that has been welded together. Tuffs have small fragments (<2 mm), volcanic breccias have larger fragments
What happens to the concentration of parent matter change as we move downwards through soil into the Earth?
It increases
How do turbulent and laminar flow differ?
Laminar: -this is idealized channel flow -In this scenario, water molecules move in parallel lines and maintain their velocities (this is what happens when you gently turn a faucet on-you may have also observed this at the Detroit airport if you have seen their laminar flow fountain) Turbulent: -In reality, flow tends to be more or less turbulent -water particles do NOT move in parallel lines and experience changes in velocity -this is what happens when you turn the sink on hard- if you look up videos of "kayak mystery move" you can observe kayakers experiencing this phenomenon -they will not move in straight lines
Viscosity
Measure of resistance to flow (i.e., maple syrup is viscous and flows slowly; orange juice is less viscous and flows more easily)
Proxy
Measurements or observations of physical variables that tell us about climate
Water
Mechanical weathering process in which water causes weathering largely by abrading rocks with the rocks that it is transporting
Abrasion
Mechanical weathering process in which water-borne particles physically smash into each other and break off pieces of each other (abrasion can make potholes: circular holes in rocks that result from the continuous grinding action of sediment that gets trapped in depressions)
Thermal expansion and contraction
Mechanical weathering process occurs in which rocks expand when warm and shrink when cool
Root wedging
Mechanical weathering process that occurs when the roots of a tree wedge into a crack in a rock and, as it grows, splits the rock
Ice wedging
Mechanical weathering process that occurs when water freezes in the cracks of rocks and expands, causing the rock to break apart
Mineral wedging
Mechanical weathering process that occurs where evaporation of water leads to the growth of crystals in cracks
Polymorph
Minerals with the same composition, but different crystalline structure -This must be part of what is going on with diamond and graphite
How much of the rock record is therefore missing on the ocean floor given the age of the Earth (4.56 billion years)?
Missing more than 95% of the Earth's 4.5 billion year record
What kinds of soils are common in Iowa?
Mollisoils
How do renewable and non-renewable resources differ?
NONRENEWABLE: these form or accumulate over millions of years, and we consider quantities present fixed. This includes coal, natural gas, iron (and a LOT of other stuff). So if we use up what is currently present, we are NOT going to get more RENEWABLE: these are either virtually inexhaustible or are relatively quickly replenished (on the scale of years to decades). Examples: sun, wind, tides
Continent-Continent
Neither of them subduct
Is there anywhere on Earth where we can observe, in a single outcrop, the complete record of Earth history?
No
Earth flows
Observe the moderate to rapid movement of water-saturated, fine grained sediment downslope, commonly on hillsides in humid areas during heavy precipitation or snowmelt
Ocean-Continent
Oceanic crust always subducts
How do felsic and mafic minerals relate to plate tectonic settings (which is associated with oceanic crust? Which is associated with continental crust?)
Oceanic crust: -MAFIC (ferromagnesium minerals) -DENSE (3.0 g/cm3) -THINNER Continental Crust: -FELSIC (more silica, non-ferromagnesium mins.) -LESS DENSE (2.7 g/cm3) -THICKER
How do oceanic and continental crust differ from each other?
Oceanic: -DENSE (3.2 g/cm3) -Thinner (7-10km) -Rocks: basalt, gabbro (more on these in a few weeks) -The older, the colder Continental: -LESS DENSE (2.7 g/cm3) -Thicker (25-70km) -Rocks: granitic, rhyolite (more on this in a few weeks) ***one plate can contain both kinds of crust***
Which state had the most earthquakes in 2014: California, Maine, Oregon, or Oklahoma?
Oklahoma
Ocean-Ocean
Older, colder subducts
When might igneous rocks not follow the rock rules, and which rock rules do they break?
Originally horizontal: ex. Plutons, dikes, batholiths Superposition: ex. dikes, conglomerate, blocks
Example of landslide
Oso, Washington landslide in March of 2014. This killed 43 people and behaved in a way that we had not predicted because of the super-saturated nature of the slope and incorrect estimation of the ages of prior mass wasting events
Transform Boundary
Plates slide past each other: -Conservative (lithosphere is neither created nor destroyed) -The Mid Ocean ridge is offset by transform boundaries (these link spreading sections of the ridge) -Depth of earthquakes at oceanic transform boundaries is limited by plate thickness -Do not get very deep earthquakes here
What is the shape of growth curves for Atmospheric CO2, world human population and global energy consumption?
Recent climate change Increases in atmospheric CO2, rate of fossil fuel (petroleum, coal, natural gas) consumption and human population growth all define exponential curves since 1900 (hockey stick).
How did the Pleistocene impact sea level, and what happens to sea level when glaciers melt?
SEA LEVEL RISES
At the equator, is salinity low or high? How about at 20-30 N and S? How about at the poles when sea ice is forming?
Salinity is a measurement of dissolved organic solids (Na and Cl being the obvious solids) that is measured in PPT (parts per thousand-grams dissolved solid per thousand grams of seawater). In the open ocean, salinity ranges from 33-37 PPT; it is variable seasonally and also in more restricted settings. Salinity in the open ocean represents a balance between evaporation and precipitation. At the poles, salinity is variable seasonally: when ice is forming, it leaves behind very cold and salty water which sinks into the deep ocean.
What major deposits do we find in Iowa, associated with limestones?
Sediment-hosted deposits: -Cu, Zn, Pb, and uranium deposits may form in large sedimentary basins -Fluids carrying metals migrate along faults, and form deposits within sedimentary rocks. -Examples: Mississippi Valley Type (MVT): Pb-Zn deposits in Iowa area. These are associated with galena, which occurs within limestones
Rock slide
Slow to rapid movement downslope of relatively intact rock layers that have detached from a sloped outcrop, and that move along a well-defined rupture surface(consolidated)
What 5 fundamental sources provide energy on Earth?
Solar nuclear fusion, the pull of gravity, nuclear fission reactions, Earth's internal energy, energy in chemical bonds
What are the major unidirectional changes in the Geosphere or solid Earth?
Solid Earth: differentiation of the Earth interior (core-mantle-crust), formation of the moon (collision with large protoplanet) and formation of continental crust are good examples of changes in Geosphere through time.
& approximately HORIZONTAL
Strata deposited under the influence of gravity should form relatively flat beds. If you see a NOT flat bed, something has happened!
What kind of a volcano is Mt. Rainier, and what is the structure of these volcanoes and the plate tectonic setting that they are associated with?
Stratovolcano: -Intermediate to felsic in composition -Symmetrical, steep slopes (~35 degrees)-these really look like our classic idea of a volcano -Interlayered materials: ash, lava, lahars. -Erupt explosively, flow very short distances because of their high viscosity (they will often form domes), and generate pyroclastic deposits -Extremely hazardous -They occur at the subduction zones and are caused by convergent boundaries. At a subduction zone, a plate with oceanic crust dives beneath the other plate and into the mantle, where it is reabsorbed. The subducted plate heats and loses water, melting magma
What does this Principle of Uniformitarianism state, and how is this related to the concept of rocks and minerals being environmental fingerprints?
The concept that the processes that have operated in the past and the processes that are operating right now are the same -Earth works a certain way -Same fundamental processes are still the same
How deep does light penetrate in the open ocean, and how does it impact where animals live?
The dysphotic zone (200-1,000 m): light rarely penetrates here, and no photosynthesis can occur -Plankton (animals at the mercy of the ocean's currents) and phytoplankton (photosynthetic plankton) tend to live in surface waters, since phytoplankton form the basis of the marine food chain and need light to photosynthesize
Aphanitic vs. Phaneritic
The individual crystals in an aphanitic igneous rock are not distinguishable to the naked eye. ... Phaneritic (phaner = visible) textures are typical of intrusive igneous rocks, these rocks crystallized slowly below Earth's surface. As magma cools slowly the minerals have time to grow and form large crystals.
What determines what kind of metamorphic rock we will end up with-what factors are important?
The metamorphic rock is dependent on: -Its protolith (parent rock) -The degree of metamorphism (the time over which a rock is being metamorphosed) -The specific ratios of heat/pressure/fluids that the rock is exposed to
Chemical Weathering
The process that breaks down rock through chemical changes
Strain
The resultant deformation, which manifests as changes in shape or size
Leaf margin shape
The smoothness or jaggedness of leaf margins (and points) can be a useful proxy for temperature. Leaves raised farther south have smooth margins, while leaves in the north have jagged margins. Smooth = warmer climate / Jagged = colder climate
Angle of repose
The steepest angle at which a pile of unconsolidated sediment remains stable
What is the average rate of coastal erosion in the United States?
There are 30 coastal states in the US, and the average rate of coastal erosion is 2-3 feet each year
Mechanical/physical weathering
Type of weathering caused by the effects of changing temperature on rocks, causing the rock to break apart.
how would a hydrograph differ for a rural vs. an urban area (and why would it differ)?
Urban vs. rural drainage: asphalt and concrete surfaces are impermeable, and cause runoff to spike rapidly after a storm. This shifts our hydrograph: stream discharge peaks higher and earlier than it would in a rural system. You should be able to recognize a hydrograph of a rural vs. an urban storm event for the second exam.
How is uniformitarianism related to the concept of rocks and minerals being environmental footprints?
Use it to understand the rock record and understand how things haven't changed but the environment has
What are our three different kinds of hydrothermal deposits?
VEIN: solution moves along fractures, cools, and precipitates within cracks DISSEMINATED: precipitated as minute masses through entire rock mass (small amounts everywhere!) SURFACE: where magma is near the surface, dissolved metals may precipitate when water cools
Where crust gets recycled/earthquakes at convergent boundaries:
Wadati-Benioff zones. You can see the outline of the subducting plate! This is why we see such deep earthquakes: they occur in the subducting slab as it descends into the mantle. When we look at the record of seismicity in this region, we can also see seismic gaps in the Andes-these areas are likely to experience earthquakes in the future
How do plate boundaries relate to hazards, like earthquakes and volcanoes?
We can also blame plate tectonics for our non-hot spot volcanoes, like the Cascade volcanoes on the west coast of the United States, which are the result of ocean-continent convergence and resultant melt at depth.
What can we learn about by studying lithified dune deposits and their crossbeds? Know how to interpret current direction from an image (we talked about this with ripples and cross beds, too!).
We can use lithified dune deposits to infer past wind conditions, as well as paleoclimate (if we find dunes, we know it was arid)
Did dinosaurs have feathers? What sounds did some of the Cretaceous (specifically, 66-68 MYA) birds make?
We've learned that dinosaurs (many, many dinosaurs) had FEATHERS and that birds evolved from dinosaurs, and that some birds that lived alongside dinosaurs quacked like ducks and flapped their wings like bats.
How does magma silica content relate to explosivity?
What determines the explosiveness of volcanic eruptions is the presence of silica tetrahedra which can link to form sheets and chains, reducing the magma's ability to flow, increasing its viscosity, and trapping gases
Half life example
What happened February 15th, 2013 in Russia?: We found a piece of the Russian meteorite! And we want to know how old it is. We take it to a lab and analyze it, and find out that the ratio of Uranium 238 to Lead 206 is 50% U-238, and 50% Pb-206. ?: How many half lives have elapsed, and how old is the meteorite? 1) We use this parent and daughter pair: U-238 and Pb-206 2) The half life for this pair is: 4.5 GA 3) Since one half life has passed, this meteorite is... 4.5 GA
What are the ways by which humans impact flooding, and how do we engineer rivers to flood less?
What impacts? 1) Urban vs. rural drainage: asphalt and concrete surfaces are impermeable, and cause runoff to spike rapidly after a storm. This shifts our hydrograph: stream discharge peaks higher and earlier than it would in a rural system. You should be able to recognize a hydrograph of a rural vs. an urban storm event for the second exam. 2. Climate change: for every 1 F increase in temperature, the atmosphere can hold 4% more water. This is expected to lead to more frequent and more severe storms. How? A. Channelization: concrete your channel. This allows the channel to hold more water, and water passes through areas rapidly. However, areas downstream experience increased erosion B. Artificial Levees: these structures can keep rivers within their (now higher) banks during flood events. However, they are not fail-proof and are expensive to construct C. Dams: these are useful to a point, but have short lifespans since they trap sediment, are expensive, and cannot stop all floods
Could you make a deep water wave in a coffee cup?
Yes, of course. Remember, whether a wave is deep water or shallow water depends only on its wavelength and the depth of water it's traveling through. For example, when you blow on your coffee cup, you make capillary waves with tiny wavelengths
Debris avalanche
a VERY FAST flow of water-saturated rock, dirt, vegetation, and sometimes ice
streams transport sediment:
a. Bed load b. Suspended load c. Dissolved load
Specific retention
amount of groundwater that is retained within source as a ratio to the total amount of sediment/rock. Small grain sizes will increase retention, and higher retention = less water coming out = less good aquifer!
Specific yield
amount of groundwater that will drain by gravity as a ratio to the total amount of sediment/rock. High specific yield = good aquifer
bajada
an apron of sediment along a mountain front
floodplain
an area along a river that forms from sediments deposited when the river overflows its banks
ventifact
angular rocks, also sculpted by the wind
Combustion
basic chemical process of releasing energy from a fuel and air mixture
Glacial erratics
big, ice transported boulders that are not derived from bedrock near their present site (they have been transported). We recognize these based on their alien nature due to their surroundings-they are great big rocks that don't match the types of rocks present at the surface in an area.
Traps
can be anticlines (allow the accumulation of resources at apex) or along faults (where offset of fault brings impermeable rocks adjacent to reservoir rocks, migrating oil and gas may be trapped) -Traps can also form related to salt domes (salt rises, forming domes) -Rising oil and gas may accumulate in deformed adjacent and overlying sedimentary strata
Contamination
can come from point sources, where we have a specific and identifiable source, or diffuse sources, where contamination occurs over a large area.
Turbulent flow
can loosen and lift material from the stream bed using water pressure
Shoreface
constantly disturbed by wave action, where waves break
features of meandering streams
cutbank, point bar, meander scar, oxbow lake, levee, and floodplain
Are earthquakes distributed randomly on the Earth's surface?
deep earthquakes occur at plate boundaries and are associated with deep ocean trenches
point bar
deposit of sediment build up by a river on the inside bend of a meander
cutbank
eroded stream bank on the outside of a meander curve
Details on the different velocities that we may observe in mass wasting events
fast: in areas where there are young, geologically rugged mountains, we commonly see rapid mass wasting events.As landscapes mature, we see less dramatic downslope movement (this is what we might observe in old mountains or areas of more gentle topography, like on the slopes of Iowa).
Be able to define stress and strain, and also be able to sketch blocks that are experiencing compressive forces, tensional/extensional forces, and shear forces.
force applied to a given area)
What are nonrenewable resources?
from at time scales much slower than which they are used: anything that forms at geologic rates and consumed at current human rates is nonrenewable
Examples of great aquifers include:
gravel, sands, sandstones, fractured limestones, fractured basalt
WAVELENGTH
horizontal distance from crest to crest, or from trough to trough
Glacial extent
how extensive were glaciers, globally? Lots of glaciers = colder climate
Rural Hydrograph
hydrograph
If we melted the Antarctic ice sheet, by how much would sea level rise?
if we manage to melt this glacier, sea level will rise globally by 60-70 meters (so as much as a 15 story office building)
Beach nourishment
in these projects, sand is often pumped from offshore onto beaches. This does build a beach! Problem: it damages sea life, is wildly expensive, and that sand continues to leave like it did before, so you end up without a beach again pretty soon
Storm wave base
is the area on the bottom of the ocean that is only stirred up during storm events when longer wavelength waves impact an area
Ocean-ocean subduction zone:
island arc from subducting plate melting
inselburg
isolated mountain remnants. This name literally means "island mountains", which is a pretty thought!
How do we attempt to control the coastline?
jetties, groins, seawalls, and breakwalls
carbon moves into and out of reservoirs over both...
long and short time scales
Salt water intrusion
near coastal areas, overpumping can cause the saltwater margin to migrate and can introduce saltwater into wells not on the coast. This can also happen as a result of sea level rise.
normal fault
normal
Rain Shadow or Mid-latitude deserts and steppes
occur as a result of rain shadows created by mountains Example: Washington and Oregon
Why do scientists think that dumping iron in the southern ocean could help slow climate change?
one potential avenue for mitigating climate change is to artificially cause these blooms: scientists think we can dump iron into the oceans where it is limiting, and drive blooms. This might not actually work, though, and also may have unintended consequences.
Changes in incoming solar insolation
our current sun is warmer than our sun was 4.56 GA, solar luminosity has increased through time
stable isotopes
preserve environmental signatures recorded at the time that they get incorporated into material, like shells and ice sheets (a really precise temp proxy)
Varves
rock formed when stratified drift (originally lain down by glacial meltwater) is lithified. These often form annual couplets- we can count these and keep track of time. Because of this, these are powerful tools for interpreting paleoclimate and studying, in very fine detail, the past history of an area
What is my #1 rule for getting preserved, and why?
rule: a bad place to live is a good place to die why: 1) life assemblage: loss through biological agents 2) death assemblage: loss through rock forming processes, decay/necrolysis (break up after death) 3) preserved as a fossil! : loss through erosion, metamorphism, etc. 4) actually found and curated: if this doesn't happen, you don't really "count" as a fossil (yet)
Suspended load
sediment is suspended in the water (turbulent flow is good at keeping particles suspended). This will support medium to small clasts
playa lakes
shallow evaporate lakes that form in flat "playas" on the valley floors
Dissolved load
soluble ions that have entered the fluid through dissolution are carried along in the water
recurrence interval
statistical average of number of years between flows of a certain peak discharge or streamflow
Recessional moraines
tell us about where glaciers were and their patterns of retreat
What is an example of an Ocean-Continent Convergence?
the Andes are at a convergent boundary (Nazca Plate subducting under the South American Plate)
drainage basin
the area from which a single stream or river and its tributaries drains all of the water
The zone of saturation
the area of 100% saturation
water table
the level below which pore space is 100% saturated
dendrochronology
the scientific study of tree rings
porosity
the space within rocks and bodies of sediment
WAVE PERIOD
the time it takes between the passage of two successive crests
Greenhouse effect
the warming that results when solar radiation is trapped by the atmosphere
Revetments/Riprap
these are basically piles of rocks or interlocking concrete slabs that can be used to armor the beach. These are easy to install and maintain and physically do a good job of holding the shore in place. However, they do not protect structures behind the wall, which are still vulnerable during storm events
cone of depression
these occur when pumping locally lowers the water table. It can cause shallow wells within the cone of depression to go dry
What does it mean for a stream network to have a dendritic shape?
they have a branching pattern of tributaries joining together that looks like trees
Dissolution
this is a chemical weathering process wherein soluble material dissolves into the stream and is carried away
bed load
this is transport for larger clasts (cobbles and boulders). Sediment bounces and rolls across the stream bed
Between turbulent and laminar flow, which is more common in actual streams?
turbulent
urban hydrograph
urban
What are the common glacial deposits that allow us to interpret past glacial events?
varves
Waveheight
vertical distance between the crest and the trough of a wave
OUTWASH
very large fluvial systems at the terminus of glaciers - braided rivers: form outwash plains: relatively flat, gently sloping plain consisting of stratified drift deposited by meltwater streams leaving a glacier.
What is bitumen?
viscous, degraded form of oil
Abrasion
water-borne particles physically smash into each other and break off pieces of each other.
. Given an unconfined vs. a confined aquifer, which might require more pumping, assuming that both wells were at the same depth? Your explanation should include the term "artesian wells".
we intentionally intersect groundwater by digging down to reach it. In an unconfined aquifer, you need to drill and pump at the level of the water table-this is the highest water will rise. In a confined aquifer, the water is under pressure due to the weight of overlying water and overlying rocks and sediment. Water will rise to the level of the potentiometric surface-this can give us artesian wells, which do not need to be pumped -in an unconfined aquifer, you have to pump the well- in artesian wells, water will flow out on its own
Subsidence
when water is withdrawn from aquifers, grains can compact into empty air filled space and the whole ground surface can subside. This is illustrated very well in San Joaquin Valley in California.
capillary fringe
where water rises into pore space above the water table due to capillary action
LOESS
widespread, unstratified blanket of windblown silt that can accumulate alongside and also downwind of glacial outwash rivers. This is very fine sediment that is often easily eroded. We find this throughout the Midwest (Loess Hills, IA)
