GEOL 101 Final

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What is the age of the oldest rocks on Earth? What is the age of the oldest rocks known? Why is there a difference - ie why can we say the Earth is 4.68Ga years old, when the oldest rocks have only been dated to ~4Ga?

-In the first half-billion years of existence, the Earth might have been so hot that rocks in the crust remained above the closure temperature for minerals -Earth has cooled sufficiently to host oceans of water within only a couple of hundred million years of its formation, suggesting that intense bombardment of the Earth by meteorites just prior to ~4Ga destroyed or remelted any crust that existed and vaporized the earliest oceans.

What orogenic (mountain building) events led to the formation of Appalachian Mountains?

-Laurentia's eastern margin rammed into a volcanic island arc and other crustal fragments -Resulting collision (Taconic orogeny) deformed and metamorphosed strata deposited in the continent's passive-margin basin -Produced mountain range (Appalachians)

Order the steps in the creation of mantle-plume related volcanism.

1) A mantle plume, a regionally restricted column of hot rock, rises inside the asthenosphere. 2) AT the base of the lithosphere, the rock in the mantle plume partially melts. 3) Magma intrudes upwards into the plate. 3) Magma erupts to form a volcano.

Outline the progression of hot spot related seamount formation.

1) A volcanic island forms over a hot spot. 2) The movement of the tectonic plate carries the volcano away from the hot-spot source, causing it to go extinct. 3) As the island ages, it cools and subsides. 4) The island erodes until it is no longer emergent, and it becomes an underwater seamount.

Order the steps in neocrystallization.

1) Protolith minerals are consumed by chemical reactions. 2) Thin clay minerals begin to align. 3) Clay grains flatten out and become parallel to one another 4) Small garnets appear (In neocrystallization, chemical reactions digest minerals of the protolith to produce new minerals. Compression and shear stresses align thin clay minerals. Continued compression flattens out clay minerals parallel to each other. Due to chemical reactions, small garnets form.)

Order the steps in the formation of an angular unconformity.

1) Sediments are deposited and lithified 2) Regional mountain building takes place, and sedimentary layers are folded into anticlines and synclines. 3) Erosion takes place 4) Sediments are deposited on top of an erosional surface

Order events chronologically that can lead to a subduction-related tsunami.

1) The overriding plate "sticks" to the subducting slab. 2) The overriding plate deforms, and strain builds. 3) Slip occurs, and the overriding plate movies back into position, displacing a large amount of the seafloor. 4) A bulge of water forms at the sea surface and spreads out as a series of waves.

Be able to explain, identify, and describe anticlines, synclines, monoclines as well as basins and domes

3 Types of Folds ♣ Anticline • Arch-like fold; limbs dip away from the hinge (angled downward; apex is highest point) ♣ Syncline • Through-like fold; limbs dip toward the hinge (angled upward; apex is lowest point) • Anticlines and synclines frequently alternate in series. ♣ Monocline • A fold like a carpet draped over a stair step o Generated by blind faults in the basement rock o These faults do not cut through to the surface o Instead, displacement folds overlying sedimentary cover. Fold Identification ♣ Folds are also described by their 3-D shape. Dome - Fold with appearance of overturned bowl. o Erode to expose old rocks in center; younger rocks outside o Result from crustal warping Basin - Fold shaped like a bowl o Erode to expose young rocks in center; older outside o Result from crustal subsidence

Be able to explain the 3 types of stress

3 Types of Stress -Compression ---> Convergent boundaries ---> Continental collision ---> Reverse/Thrust faults -Tension ---> Divergent boundaries ---> Continental rift ---> Normal faults -Shear ---> Strike-slip fault lines ---> San Andreas Fault

Which of the following statements about growth rings of trees is FALSE? Choose one: A. Each tree ring represents one year of growth. B. The thickness of a tree ring can indicate the rate of growth of the tree. C. Interpreting tree rings is, in a sense, a method of paleoclimatology. D. A thin ring indicates a warm, wet year; a thick ring represents a cold, dry year.

A thin ring indicates a warm, wet year; a thick ring represents a cold, dry year. (The opposite is true; a thick tree ring indicates a warm, wet year since the tree grows faster during warmer, wetter years.)

Which of the following statements about drainage basins and divides is FALSE? Choose one: A. A trunk stream carries water away from a drainage basin. B. Streams on the west side of the continental divide flow into the Pacific Ocean. C. A watershed is a ridge that separates one catchment from another. D. Precipitation that falls on the east side of the continental divide flows to the Atlantic Ocean.

A watershed is a ridge that separates one catchment from another. (A drainage divide separates one catchment from another, not a watershed.)

Be able to compare and contrast relative and absolute dating techniques.

Absolute dating = a numerical age is determined. Relative Dating = Events are put in relative order RELATIVE DATING: Fossil correlation, Lithologic correlation -Fossil Correlation: using fossils w/ known stratigraphic ranges to determine approximate temporal equivalence of two bodies of rock -Lithologic correlation: use physical & chemical characteristics of rocks to determine that spatially isolated strata were once continuous (through original lateral continuity). Because a single locality does not provide strata that span in age throughout Earth's history, fossil correlation was required to provide time equivalence for units that are geographically isolated. With successful correlation, rock sequences from all parts of the world could be brought together to form an accurate sequence of relative time (the geologic column). (A stratigraphic formation is a recognizable layer of a specific sedimentary rock type or set of types that were deposited within a certain time interval and can be traced over a broad region). ABSOLUTE DATING: Radiometric Dating -Radiometric Dating: Dating geologic events in years by measuring the ratio of parent radioactive atoms to daughter product atoms within a mineral extracted from the rock of interest and then comparing this ratio to the known half-life of for the nuclear reaction.

Be able to differentiate between stress and strain.

Active tectonics put rocks under stress which can lead to deformation Stress: A measure of the amount of force applied over a given area; 3 Types: Compressional, Tension, Shear Strain: The amount of deformation (distortion) that an object experiences compared to its original size and shape

Which of the following statements is FALSE? Choose one: A. Overuse of the waters of the Colorado River has reduced it to a mere trickle near its mouth. B. Dead zones can form where rivers empty pollutants into the oceans. C. Urbanization creates impermeable surfaces that prevent infiltration after rainfall events. D. Agriculture (planting crops on floodplains) reduces sediment load into nearby rivers.

Agriculture (planting crops on floodplains) reduces sediment load into nearby rivers. (Farmland has less plant cover than natural grassland or forest. The bare ground between rows of crops can erode and send large volumes of sediment into nearby rivers.)

Identify examples of rock deformation. Bending Shearing Shortening Breaking

All of the above!

The Taconic, Acadian, and Alleghenian orogenic events all led to uplift in the region of modern ____. a) Rockies b) Appalachians c) Alps d) Himalayas

Appalachians

What feature(s) characterize most metamorphic rocks? a) Assemblage b) Silica Content c) Grain size d) Texture

Assemblage Texture (Metamorphism may result in new minerals growing within the rock. These minerals make up a metamorphic mineral assemblage. Metamorphism may also produce a specific arrangement of these mineral grains, which is dubbed as a metamorphic texture. When these changes occur during metamorphism, the resulting metamorphic rock is markedly different from the original rock.)

How does the type of bedrock (hard rock—ie igneous or metamorphic rocks) vs loose sand and gravel influence the amount of damage done by an earthquake? WHY (how is the velocity of the wave altered)?

Bedrock transmits waves quickly = less damage Sediments bounce waves = amplified damage ^ Landslides, Avalanches, Liquefaction Landslides and Avalanches -Shaking causes slopes to fail -Hazardous slopes bear evidence of ancient slope failures -Rockslides or snow avalanches follow earthquakes in uplands Liquefaction -Waves liquefy H2O-filled sediments. -High pore pressures force grains apart reducing friction. -Liquefied sediments flow as a slurry. -Sand becomes "quicksand": clay becomes "quickclay." ♣ Sand dikes ♣ Sand volcanoes ♣ Contorted layering -Water-saturated sediments turn into a mobile fluid -Land will slump and flow -Building may topple over intact

Which statement is TRUE? Choose one: A. P, S, L, and R are all body waves that pass through the Earth's interior. B. S-waves travel twice as fast as P-waves. C. The hypocenter (focus) is the point on Earth's surface directly above the epicenter. D. Body waves pass through Earth's interior, whereas surface waves travel at the Earth's surface.

Body waves pass through Earth's interior, whereas surface waves travel at the Earth's surface. (L and R are surface waves (not body waves); the epicenter is above the focus; and S-waves travel at 60% the speed of P-waves. The correct choice describes the nature of body waves and surface waves.)

Be able to distinguish between ductile and brittle deformation and explain the factors that control rock behavior

Brittle Deformation -Rocks break by fracturing (faulting) ---> Brittle deformation occurs in the shallow crust ---> (Think of a dinner plate breaking) Ductile Deformation o Rocks deform by flow & folding ♣ Occurs in the deeper crust What controls how a rock will behave? (Brittle vs. Ductile) Temperature ---> Hot rocks are more ductile than cool rocks. Pressure ---> Rocks under high pressure are more ductile Deformation Rate ---> Sudden changes produce brittle behavior Rock Type

How did tectonic conditions change during the Proterozoic Eon? A. Rifting resulted in the formation of the Basin and Range Province of North America. B. Sea levels rose to form shallow epicontinental seas. C. Broad, stable cratons formed in continental interiors. D. Convergence of crustal fragments with continents created exotic terranes.

Broad, stable cratons formed in continental interiors. (Plate tectonic conditions became more similar to what is observed today, with larger oceanic plates and the development of broad, stable cratons in continental interiors.)

Be able to compare and contrast weather and climate.

Climate o Long-term weather patterns of an area Weather o Current state of the troposphere (lower atmosphere!) o Short term variations

Which plate tectonic settings would you be most likely to find foliated metamorphic rocks?

Collision boundaries & Transform boundaries Dynamic Metamorphism o Breakage of rock by shearing at a fault zone ♣ Transform Plate Boundaries! • Causes Foliation! Regional Metamorphism -Tectonic collisions deform huge "mobile belts." -Directed compression thickens mountains. ♣ Rocks caught up in mountain buildings are... • Heated via the geothermal gradient and plutonic intrusions • Squeezed and heated by deep burial • Smashed and sheared by differential stresses ♣ CONVERGENT BOUNDARIES o Regional metamorphism creates foliated rocks o This type of metamorphism is, by far, the most important in terms of the amount of rock altered

Be able to recognize a "cone of depression" and explain how or why it forms.

Cone of Depression o Created by drawing down water table by pumping a well. o Overdraft occurs where pumping is too rapid, well goes dry. o What are some other problems associated w/ use of wells? ♣ Lack of filtering in karst regions ♣ Limited amounts of groundwater in some rock types ♣ Subsidence ♣ Salt-water invasion

What major classes of organisms appeared in the Paleozoic?

Conodonts, trilobites, mollusks, brachiopods, and echinoderms.

Be able to discuss how crustal root thickening is related to the height of a mountain.

How crustal root thickening is related to the height of a mountain? Why does orogenic collapse occur?

Crustal Roots & Mountain Heights • High mountains are supported by thickened lithosphere (Crust). • Thickening is caused by collisional orogenesis. o Average continental crust - 35 to 40 km thick o Beneath orogenic belts - 50 to 70 km thick • This thickened crust helps buoy the mountains upward. Orogenic Collapse - Uplift has limits! • The Himalayas are the maximum height possible. Why? • There is an upper limit to the mountain heights. o Erosion accelerates with height o Weight of high mountains overwhelms rock strength. ♣ Deep, hot rocks eventually flow out from beneath mountains. ♣ The mountains then collapse downward like soft cheese. o Uplift, erosion, and collapse exhume deep crustal rocks.

Explain how steps can be taken to protect people from the effects of eruptions.

Danger assessment maps -Delineate danger areas ♣ Pyroclastic flows ♣ Lahars ♣ Landslides o Used for planning, zoning Evacuation - Moving those at high risk saves lives -Mt. St. Helens - Timely evacuation saved hundreds. -Sometimes eruptions don't occur; large expenses Diverting flows - Flowing lava can be diverted -Explosives -Heavy equipment -Seawater

Be able to identify ways that mitigate volcanic hazards.

Danger assessment maps o Delineate danger areas ♣ Pyroclastic flows ♣ Lahars ♣ Landslides o Used for planning, zoning Evacuation - Moving those at high risk saves lives o Mt. St. Helens - Timely evacuation saved hundreds. o Sometimes eruptions don't occur; large expenses Diverting flows - Flowing lava can be diverted o Explosives o Heavy equipment o Seawater

What is a metamorphic grade, and how can it be determined?

Different minerals are stable as T and P changes. -Grade is a measure of metamorphic intensity. -Low-grade - slight changes -High grade - Intense changes Metamorphic Assemblages -Metamorphic grade determines mineral assemblages. -As grade increases, new and larger minerals form.

What is metamorphic foliation, and how does it form?

Differential Stress (Directed Pressure) -Pressure that is greater in one orientation. -A commonplace result of tectonic forms. -Rocks change shape slowly without breaking. -Differential stress causes minerals to align. -Preferred platy mineral alignment is called foliation. ---> Foliation imparts a layered or banded appearance. ---> Rocks commonly break parallel to foliation planes. -Foliations develops perpendicular to the applied compressional stress.

What life forms appeared in the Mesozoic?

Dinosaurs, mammals, birds, and swimming reptiles

What is the primarily difference between dip-slip and strike-slip faults?

Dip-Slip: Sliding is parallel to fault plane dip Thus, blocks move up or down the slip of the fault Strike-Slip: Fault motion is parallel to the strike of the fault

Be able to describe how discharge changes as you move downstream (toward mouth of stream). -Why might this be different in desert climate or a temperate climate?

Discharge • Velocity is not uniform in all areas of a channel o Friction slows water along channel edges. Friction is... ♣ Greater in wider, shallower streams ♣ Lesser in narrower, deeper streams o In straight channels, highest velocity is in the center o Few natural channels are straight • Water within a stream channel moves at different velocities, creating cut banks (higher velocity) and point bars (lower velocity)

Be able to recognize and explain the geologic settings of dendriticand trellis drainage basins. (What causes different drainage patterns to form?)

Drainage Networks o Drainage networks often form geometric patterns o These patterns reflect underlying geology o Common drainage patterns ♣ Dendritic - Branching, "treelike" due to uniform material ♣ Trellis - Alternating resistant and weak rocks (like a ladder)

Be able to define what a drainage basin (watershed) is and describe the significance of a continental divide

Drainage basins = Watersheds o Land areas that drain into a specific trunk stream o Also known as catchments or watersheds o Divides are uplands that separate drainage basins Continental Drainage Divides o Watersheds exist in a variety of scales ♣ Tiny tributaries ♣ Continental rivers o Large watersheds... ♣ Feed large rivers ♣ Section continents Continental divides separate flow to different oceans

Compare and contrast brittle and ductile deformation

Ductile Deformation -Wherein the strain is irreversible o Rocks deform by flow & folding ♣ Occurs in the deeper crust Temp: Hot rocks are more ductile than cool rocks Pressure: Rocks under high pressure are more ductile Brittle (Fracture) -Irreversible strain wherein the material breaks o Rocks break by fracturing (faulting) ♣ Brittle deformation occurs in the shallow crust Temp: Cool rocks --> Brittle Pressure: Rocks under low pressure are more brittle Sudden changes will produce brittle behavior

Select statements true of ductile deformation in solids. A. During ductile deformation, rocks can break or crack into pieces. B. Ductile deformation usually occurs at great depths and high temperatures. C. Ductile deformation is usually preceded by small amounts of elastic deformation. D. During ductile deformation, rocks can fold or bend.

Ductile deformation usually occurs at great depths and high temperatures. During ductile deformation, rocks can fold or bend.

Select the statement(s) true of the relationship between glaciation and sea level. Choose one or more: A. During warmer climates, glaciers melt and sea level rises. B. During times of cooler climates, glacial ice accumulates in the oceans, causing sea level to rise. C. During times of cooler climates, the amount of evaporation from the oceans decreases, causing sea level to rise. D. The amount of glacial ice stored on land affects global sea level.

During warmer climates, glaciers melt and sea level rises. The amount of glacial ice stored on land affects global sea level. (During a cold climate, water evaporated from the oceans can precipitate as snow over the continents, where it accumulates into glacial ice, resulting in a decrease in global sea level. After the end of the last ice age, sea level rose at least 120 meters globally as glacial ice melted and returned to the ocean basins as liquid water. In the last 100 years, global sea level has risen approximately 20 cm, about half of which can be attributed to the melting of ice sheets and glaciers.)

The Hadean is a time in Earth history when: a) the first abundant shelly organisms appear in the fossil record b) Earth's interior was so hot that a solid outer crust, if present, was likely being extensively remelted c) stable continental interiors, termed cratons, first formed d) the dinosaurs appeared and came to dominate large-scale terrestrial life

Earth's interior was so hot that a solid outer crust, if present, was likely being extensively remelted

▪ Be able to discuss EQ prediction. --What can we do and what can't we do?

Earthquake Prediction • Can we predict earthquakes? Yes and no. o They CAN be predicted - long term (10s-100s of years) o They CANNOT be predicted short-term (can't quantify). Seismic hazards are mapped to assess risk. This information is useful for... o Developing building codes o Land-use planning o Disaster planning Long-term predictions o Probability of a certain magnitude earthquake occurring on a time scale of 30 to 100 years, or more. o Based on the premise that earthquakes are repetitive. o Seismic gaps, places that haven't slipped recently are more likely candidates. Short-term predictions o Goal: The location and magnitude of a large earthquake o Currently no reliable short-range predictions are possible o Earthquakes do have precursors ♣ Clustered foreshocks ♣ Crustal strain ♣ Stress triggering ♣ And, possibly.... • Water level changes in wells • Gases (Rn, He) in wells • Unusual animal behavior

▪ Be able to identify the scope of the geologic time scale and be able to describe how the time scale is subdivided in to smaller units of time. (Eons, Eras, Periods, & Epochs) -You should be able to identify our current eon, era, period, and epoch!

Eon: Phanerozoic Era: Cenozoic Period: Quaternary Epoch: Holocene/ Anthropocene

Be able to describe how earth's land distribution, atmosphere, and life forms have changed through time. -You should be able to identify the order of appearance of select forms of life (insects, mammals, fish, amphibians, dinosaurs, reptiles, etc)

Eukaryotic Cells ---> Corals & Shellfish ---> Insects ---> Reptiles ---> Dinosaurs ---> Mammals ---> Flowering Plants ---> Homo sapiens

Be able to describe what exhumation is, why it occurs, and why it is important.

Exhumation: refers to the overall process by which deeply buried rocks end up back at the surface

What is exhumation? Why does it occur during orogenic (mountain) collapse?

Exhumation: refers to the overall process by which deeply buried rocks end up back at the surface) HOW IT WORKS: when crust collides, the rock in the middle squeezes upward.

Also know what a fault system is and the structures that they can produce! -Horsts & Graben, Basin & Range Formations

Faults commonly occur in groups called fault systems. o Due to regional stresses that create many similar faults. Thrust fault systems o Stack fault blocks on top of one another o Act to shorten and thicken the crust o Result from horizontal compression Normal Fault System o Fault blocks slide away from one another o Fault dips often decrease with depth, joining a detachment o Blocks rotate on faults and create half-graven basins o Act to stretch and thin the crust o Result from horizontal extension (pull-apart) stress. o Graben-Horst

How did the Cambrian Explosion of life change the nature of Earth?

First abundant animals complicated the world food web thru the introduction of more abundant filter and bottom (deposit) feeders, as well as large, mobile predators and the first biogenic reefs Carnivores likely induced selection pressure favoring numerous defensive structures (thick shells, spines) and behaviors (burrowing, active swimming).

Select probable outcomes for rock that was once near the surface but is carried to depth in a mountain belt through continental collision. A. Flow folds develop. B. Foliations develop. C. Cleavage planes develop. D. Phenocrysts develop.

Flow folds develop Foliations develop (Rock that is carried to depth in a mountain belt via continental collision undergoes metamorphism. The rock exhibits plastic behavior that allows flow folds and foliations to develop.)

Distinguish attributes of crustal deformation as being associated with folding or faulting. Compressional Stress Bending of geologic materials Ductile deformaton Brittle deformation

Folding: Compressional Stress Bending of geologic materials Ductile deformaton Faulting: Brittle deformation (Folds are geologic structures in which rocks bend, or exhibit ductile deformation, under compressional stress.)

What is a tsunami, and why does it form? What tectonic setting has the highest probability of causing tsunami? What geologic setting conditions make a tsunami most deadly?

Form when earthquakes change the shape of the seafloor. -Faulting drops the seabed; thrusting raises it. -This displaces the entire volume of overlying water. -A giant mound (or trough) forms on the sea surface. -This feature may be enormous (up to 10,000 mi2 area) -Feature collapse creates waves that race rapidly away. Tsunami waves • Influence entire water depth • Have wavelengths of several 10s to 100s of kilometers • Wave height and wavelength unaffected by windspeed • Wave velocity maximum several 100s of kph • Waves come ashore as a raised plateau of water that pours onto the land • Tsunamis are so wide (measured perpendicular to shore) that, like a plateau of water, they submerge the land. Tsunami destruction of the coast depends opon... -Offshore bathymetry o Broad shallows increase amplitude but sap wave energy o Quick deep-to-shallow transition - Deadliest condition ♣ Waves have maximum energy ♣ Wave heights are modest ♣ Water pours onto land as a sheet -Topography of shore o Broad, low land - Maximum damage o Steep rise of land - Less damage

Be able to explain the concept of stratigraphic correlation, and how fossil succession and rock lithologic correlation are used to create a global strat column.

Fossil correlation, Lithologic correlation -Fossil Correlation: using fossils w/ known stratigraphic ranges to determine approximate temporal equivalence of two bodies of rock -Lithologic correlation: use physical & chemical characteristics of rocks to determine that spatially isolated strata were once continuous (through original lateral continuity). Because a single locality does not provide strata that span in age throughout Earth's history, fossil correlation was required to provide time equivalence for units that are geographically isolated. With successful correlation, rock sequences from all parts of the world could be brought together to form an accurate sequence of relative time (the geologic column). (A stratigraphic formation is a recognizable layer of a specific sedimentary rock type or set of types that were deposited within a certain time interval and can be traced over a broad region).

Be able to identify the greenhouse gases and their relative affect on climate

Be able to describe how incoming solar radiation is reflected, absorbed, and transferred throughout the Earth system

Greenhouse Effect • Water vapor, carbon dioxide, and methane in Earth's atmosphere absorb thermal energy and reradiate it, warming the lower atmosphere o More Greenhouse gases - warmer; less Greenhouse gases - cooler 1) Solar radiation passes thru the atmosphere 2) Some radiation is reflected by the atmosphere and Earth's surface 3) Solar energy is absorbed by the Earth's surface and warms it --> converted into heat, causing the emission of infrared radiation back to the atmosphere 5) Some of the infrared radiation is absorbed and re-emitted by the greenhouse gas molecules. The direct effect is the warming of Earth's surface and the troposphere. Surface gains more heat and infrared radiation is emitted again. 6) Some of the infrared radiation passes through the atmosphere and is lost in space.

Be able to explain how porosity and permeability influence ground water movement.

Ground water moves faster

What phenomena can cause metamorphism (agents of metamorphism)?

Heat (Temperature- T) Pressure (P) Differential stress Hydrothermal fluids

▪ Be able to explain how orogenesis can lead to the formation of sedimentary, metamorphic, & igneous rocks.

How Mountain Building forms Igneous, Sedimentary & Metamorphic Rocks (**See diagram**) • The weight of the mountain pushes the surface of the crust down to create a basin • Rocks once at great depth are faulted and squeezed up to the surface • Igneous pluton intrudes; contact metamorphism takes place around it

What life forms appeared in the Cenozoic?

Huge mammals (mammoths, giant beavers, giant bears, giant sloths), ape-like primates

Match the following geologic settings to the form of metamorphism which occurs at that location.

Hydrothermal - MOR Burial - Ten miles below the surface Dynamic - Fault zone Thermal - Intrusion of a pluton Dynamo-thermal - Mountain range core Shock - Meteorite impact site

Be able to differentiate between the epicenter and the hypocenter (focus) on an EQ.

Hypocenter (focus) o The spot within the Earth where the earthquake waves originate o Usually occurs on a fault surface o Earthquake waves expand outward from the hypocenter Epicenter o Land surface above the hypocenter

Explain the difference between the hypocenter (focus) and epicenter of an earthquake

How are metamorphic rocks different from igneous and sedimentary rocks?

Igneous - formed by the cooling of magma(intrusive and extrusive) Metamorphic - formed by pressure changes inside earth Sedimentary - formed by weathering, cementing, or precipitation

Describe the principle of isostasy. What is isostatic equilibrium?

Isostasy? • Surface elevation represents a balance between forces o Gravitational attraction - Pushes plate into the mantle o Buoyancy - Causes plate to float higher on the mantle • The term isostatic equilibrium describes this balance. • Isostasy is compensated after a disturbance. o Adding weight pushes the lithosphere down. o Removing weight causes the isostatic rebound. • Compensation is slow, requiring asthenospheric flow.

Be able to explain how the age of the Earth was determined to be 4.6 Ga years old.

Isotopic dating of Moon rocks Dating of meteorites Meteorites from the oldest differentiated planetesimals, those that has separated into a core and mantle, are slightly younger, and these ages are taken to be the same as the age of Earth itself. Based on these ages, therefore, researches estimate the Earth itself differentiated and became a full-fledged planet at 4.54 Ga.

Be able to differentiate among folds, faults, and joints.

Joints <--- fracture in Lithosphere -Planar rock fractures without offset ♣ Result from tensional tectonic stresses ♣ Often occur in parallel sets ♣ Minerals can fill joints to form veins ♣ Joints control weathering of rock Faults - fracture in Lithosphere -Planar fractures offset by movement across the break. ♣ Faults are abundant and occur at a variety of scales. ♣ Faults may be active or inactive ♣ Sudden movements along faults cause earthquakes Folds -Layered rocks may be deformed by COMPRESSIONAL stress into curves called folds. -3 Types of Folds ♣ Anticline • Arch-like fold; limbs dip away from the hinge (angled downward; apex is highest point) ♣ Syncline • Through-like fold; limbs dip toward the hinge (angled upward; apex is lowest point) • Anticlines and synclines frequently alternate in series. ♣ Monocline • A fold like a carpet draped over a stair step o Generated by blind faults in the basement rock o These faults do not cut through to the surface o Instead, displacement folds overlying sedimentary cover. Fold Identification ♣ Folds are also described by their 3-D shape. • Dome - Fold with appearance of overturned bowl. o Erode to expose old rocks in center; younger rocks outside o Result from crustal warping • Basin - Fold shaped like a bowl o Erode to expose young rocks in center; older outside o Result from crustal subsidence

What is the primary difference between a joint and a fault?

Joints: planar rock fractures WITHOUT offset ♣ Result from tensional tectonic stresses ♣ Often occur in parallel sets ♣ Minerals can fill joints to form veins ♣ Joints control weathering of rock Faults: planar fractures offset by movement across the break. Both are fractures in lithosphere

Be able to identify examples of Karst topography.

Karst Topography o Topography with features relating to underground solution. o Collapse may also be involved. o Surface waters diverted underground. o Features: sinkholes, sinking streams, rises, caves. Karst Topography is the term for groundwater-eroded landscapes. ♣ Groundwater is the ONLY geologic agent that creates landforms below the surface. ♣ Sink Holes ♣ Karst Towers

Be able to identify and explain the hazards (damages) associated with EQs. -Ground shaking, Liquefaction, Landslides, Fires, Disease, etc. -What is a tsunami? Which type of tectonic setting most frequently generates tsunamis?

Landslides and Avalanches o Shaking causes slopes to fail o Hazardous slopes bear evidence of ancient slope failures o Rockslides or snow avalanches follow earthquakes in uplands Liquefaction -Waves liquefy H2O-filled sediments. -High pore pressures force grains apart reducing friction. -Liquefied sediments flow as a slurry. -Sand becomes "quicksand": clay becomes "quickclay." ♣ Sand dikes ♣ Sand volcanoes ♣ Contorted layering -Water-saturated sediments turn into a mobile fluid -Land will slump and flow -Building may topple over intact Fire is a common hazard following earthquakes. -Shaking topples stoves, candles, and power lines -Broken gas mains and fuel tanks ignite a conflagration -Earthquakes destroy critical infrastructure such as water, sewer, telephone, and electric lines as well as roads. o Firefighters powerless. ♣ No road access. ♣ No water, ♣ Too many hotspots. -Good planning is crucial to saving lives. Earthquake devastation fuels disease outbreaks. o Food, water, and medicines are scarce. o Basic sanitation capabilities disabled. o Hospitals damaged or destroyed. o Health professionals overtaxed. o There may be many decaying corpses. + TSUNAMIS! Form when earthquakes change the shape of the seafloor. -Faulting drops the seabed; thrusting raises it. -This displaces the entire volume of overlying water. -A giant mound (or trough) forms on the sea surface. -This feature may be enormous (up to 10,000 mi2 area) -Feature collapse creates waves that race rapidly away.

Describe the types of damage caused by earthquakes. What is the dominant cause of loss of life?

Landslides and Avalanches o Shaking causes slopes to fail o Hazardous slopes bear evidence of ancient slope failures o Rockslides or snow avalanches follow earthquakes in uplands Liquefaction -Waves liquefy H2O-filled sediments. -High pore pressures force grains apart reducing friction. -Liquefied sediments flow as a slurry. -Sand becomes "quicksand": clay becomes "quickclay." ♣ Sand dikes ♣ Sand volcanoes ♣ Contorted layering -Water-saturated sediments turn into a mobile fluid -Land will slump and flow -Building may topple over intact Fire is a common hazard following earthquakes. -Shaking topples stoves, candles, and power lines -Broken gas mains and fuel tanks ignite a conflagration -Earthquakes destroy critical infrastructure such as water, sewer, telephone, and electric lines as well as roads. o Firefighters powerless. ♣ No road acsess. ♣ No water, ♣ Too many hotspots. -Good planning is crucial to saving lives. Earthquake devastation fuels disease outbreaks. o Food, water, and medicines are scarce. o Basic sanitation capabilities disabled. o Hospitals damaged or destroyed. o Health professionals overtaxed. o There may be many decaying corpses. + TSUNAMIS!

Explain how liquefaction occurs in an earthquake and how it can cause damage.

Liquefaction -Waves liquefy H2O-filled sediments. -High pore pressures force grains apart reducing friction. -Liquefied sediments flow as a slurry. -Sand becomes "quicksand": clay becomes "quickclay." ♣ Sand dikes ♣ Sand volcanoes ♣ Contorted layering -Water-saturated sediments turn into a mobile fluid -Land will slump and flow -Building may topple over intact

How are long- term and short- term earthquake predictions made? What is the basis for determining a recurrence interval, and what does a recurrence interval mean?

Long-term predictions -Probability of a certain magnitude earthquake occurring on a time scale of 30 to 100 years, or more. -Based on the premise that earthquakes are repetitive. -Seismic gaps, places that haven't slipped recently are more likely candidates. Short-term predictions -Goal: The location and magnitude of a large earthquake -Currently no reliable short-range predictions are possible -Earthquakes do have precursors ♣ Clustered foreshocks ♣ Crustal strain ♣ Stress triggering ♣ And, possibly.... • Water level changes in wells • Gases (Rn, He) in wells • Unusual animal behavior

Be able to discuss how the character (gradient) of a stream changes longitudinally.

Longitudinal Changes • The character of a stream changes with flow distance • In profile, the gradient describes a concave-up curve • Base level o The lowest point to which a stream can erode ♣ A ledge of resistant rock may define the local base level ♣ Erosive forces act to slowly remove the resistant layer • This acts to restore the longitudinal profile. (Valleys and Canyons o Land far above base level is subject to downcutting o Rapid downcutting creates an eroded trough ♣ Valley - gently sloping trough; sidewalls define a Vshape ♣ Canyon - steep trough sidewalls form cliffs o Determined by rate of erosion vs. strength of rock)

Why do some volcanic eruptions consist mostly of lava flows (effusive), while others are explosive and do not produce flows?

Magma Composition, Viscosity, amount of silica in magma Effusive eruptions: Under less pressure, gas forms bubbles; Dissolved gas held in magma by pressure. Produce lava flows. Explosive volcanic eruptions: Released gas propels eruption and forms ash The sudden release of accumulated gas pressure blasts the lava upward, forming pyroclastic debris. Caused by gas pressure in the more viscous magma Pressure is released explosively

Describe the differences among shield volcanoes and stratovolcanoes. Magma Composition Eruption Style Dominant Hazards Plate Tectonic Setting Reference #2. How are these differences explained by the composition of their lavas? Viscosity? Gas content?

Magma Composition: Shield volcanoes have basaltic magma; Stratovolcanoes have felsic magma Eruption style: Shield- effusive; Strato- explosive Dominant Hazards: Shield- lava flows; Strato- pyroclastic ash Plate Tectonic Setting: Shield- common product of hotspot volcanism; Strato- convergent boundaries, subduction boundaries More silica in felsic magma; makes it more viscous. "Thick and sticky." Builds up on the walls of the volcano, creating a steep slope at its sides (strato). Less silica in basaltic magma; thin and runny. Runs miles away from volcano, creating a thin "shield."

How did the Cambrian explosion of life change the nature of the living world? A. It created greenhouse conditions and eventually led to widespread epicontinental seas. B. Many defensive structures and behaviors were favored in natural selection due to the proliferation of carnivores. C. Reef-forming organisms had yet to evolve. D. Numerous filter feeders and deposit feeders and large, mobile predators complicated the world food web.

Many defensive structures and behaviors were favored in natural selection due to the proliferation of carnivores. Numerous filter feeders and deposit feeders and large, mobile predators complicated the world food web. (The living world saw an influx of filter and bottom feeders as well as larger, more mobile predators, and the first biogenic reefs. Natural selection favored those animals with defensive structures and those using defensive behaviors.)

Be able to define what the water table is and explain how it is configured in humid vs. arid climates

May be visualized as the "surface" of the subsurface materials that are saturated with groundwater in a given vicinity Configuration of Water Table: • In a humid climate, WATER TALBE MIMICS LANDSCAPE • Does not mimic landscape in arid climate • R = recharge area

What could have caused the flooding of the continents during the Cretaceous Period?

Melting of glaciers after the ice age

Describe the Mercalli, Richter, and Seismic Moment scales for measuring earthquakes. Which is quantitative? Qualitative?

Mercalli Intensity Scale o Intensity - the degree of shaking based on damage o Roman numerals assigned to different levels of damage o Damage occurs in zones o Damage diminishes in intensity with distance Richter and Seismic measure magnitude Magnitude o The amount of energy released o Maximum amplitude of motion from a seismogram. o Value is not normalized for seismograph distance o Several magnitude scales

The metamorphic grade of a rock is determined by observing the: A. pressure at which metamorphism occurs. B. metamorphic mineral assemblage. C. rock's protolith. D. temperature at which metamorphism occurs.

Metamorphic mineral assemblage (Metamorphic grade is usually assessed on the basis of the mineral assemblage making up the metamorphic rock, as well as its foliation and other textural clues (such as grain size).

How are metamorphic rocks different from igneous rocks?

Metamorphic rocks are formed by solid-state changes. (Metamorphic rock is rock that forms when preexisting rock undergoes a solid-state change in response to the modification of its environment. Metamorphism occurs at a variety of locations below the surface and as the result of a number of possible environmental changes. The resulting rock may have a metamorphic texture that is defined by the arrangement of grains within the rock.)

What type of fault system creates Horst & Graben (Basin & Range) Mountains?

Normal Fault System o Fault blocks slide away from one another o Fault dips often decrease with depth, joining a detachment o Blocks rotate on faults and create half-graven basins o Act to stretch and thin the crust o Result from horizontal extension (pull-apart) stress.

Select statements true of normal faults in regard to tsunami generation. Choose one or more: A. Along a normal fault, the hanging wall moves down, creating a depression in the sea surface, and thus preventing a tsunami from forming. B. Along a normal fault, the hanging wall moves up, displacing seawater and creating a tsunami. C. Normal faulting that results in tsunami generation can occur at or away from plate boundaries. D. Along a normal fault, the hanging wall moves down, creating a depression in the sea surface; water rushes to fill the depression and rises up, initiating a tsunami.

Normal faulting that results in tsunami generation can occur at or away from plate boundaries. Along a normal fault, the hanging wall moves down, creating a depression in the sea surface; water rushes to fill the depression and rises up, initiating a tsunami.

Compare and contrast an island arc volcanoes with a continental arc volcano.

Ocean Hot Spots -Plume under an oceanic plate ♣ Basalt erupts at the seafloor and forms a growing mound ♣ A volcano builds above sea level to form an island ♣ Then basalt will not quench and can flow long distances ♣ Lava builds upward and outward and the island grows Convergent Boundaries -Most subaerial volcanoes form at convergent boundaries ♣ Volatiles from subducting plate initiate melting. ♣ Arc volcanoes develop on overriding plate -May cut through oceanic or continental crust -The "Ring of Fire" dominates Pacific margin

Be able to identify, explain, and apply the 7 principles of relative dating to correctly order a geologic cross section

Original Horizontality- Sediments are usually deposited in horizontal layers; variance from this implies post-depositional deformation Original/Lateral Continuity- Spatially isolated bodies of sedimentary rock of identical lithology were once physically connected. Isolation resulted from erosion of a previously continuous planar bed. Superposition- In an undisturbed sequence of sedimentary rocks, younger layers are deposited on top of older layers. Cross-cutting relationships (faults & intrusions)- Features can only disrupt other features that are older than themselves. (a) Igneous intrusions are younger than the rock they intrude (b) Faults are younger than the rocks or surfaces they offset (b) Erosional surfaces are younger than the rocks into which they cut Baked Contacts- If a rock is metamorphosed as a result of contact with a hot body of magma or lava (which later crystallized to form igneous rock), the metamorphosed rock must have existed (as unaltered rock) prior to the metamorphic event. Igneous intrusion "bakes" surrounding rocks, so the rock that has been baked must be younger than the intrusion. Inclusions- If a rock contains pieces of another body of rock, then it must be younger than the donor rock.

Be able to explain why orogenic collapse occurs. (Why there is an upper limit to mountain height?)

Orogenic Collapse - Uplift has limits! • The Himalayas are the maximum height possible. Why? • There is an upper limit to the mountain heights. o Erosion accelerates with height o Weight of high mountains overwhelms rock strength. ♣ Deep, hot rocks eventually flow out from beneath mountains. (sideways) ♣ The mountains then collapse downward like soft cheese. o Uplift, erosion, and collapse exhume deep crustal rocks.

Earthquakes are caused by the release of seismic waves. Describe each of the types of seismic waves listed (body or surface, velocity, type of motion, etc). Primary waves Shear/Secondary Waves Love Waves Rayleigh Waves

P-waves: Body waves, fastest velocity, most efficient at transmitting energy, parallel to wave direction S-waves: Body waves, can't travel through liquids, perpendicular to wave direction Love waves: Surface waves Rayleigh waves: Surface waves

What is a protolith? What is the protolith for phyllite? Marble? Quartzite?

Parent rocks are called "protoliths." -Metamorphism can occur to any protolith. -Igneous, Sedimentary, or Metamorphic! Protoliths undergo pronounced changes in... -Texture -Mineral Assemblage (Composition) Shale/Slate --> Phyllite Fossiliferous limestone --> Marble Quartz sandstone --> Quartzite

Be able to compare and contrast permanent and ephemeral streams. Which forms in humid/temperate climates? Which is dry/arid climates?

Permanent Streams ♣ Water flows all year ♣ At or below water table ♣ Humid or temperate • Sufficient rainfall • Lower evaporation • Discharge varies seasonally Ephemeral streams ♣ Do not flow all year ♣ Above the water table ♣ Dry climates • Low rainfall • High evaporation ♣ Flow mostly during rare flash floods.

If an elongate crystal grows within a metamorphic rock, would you expect its long axes to be aligned parallel to the direction of maximum compression, or perpendicular to it?

Perpendicular

What is a Wadati- Benioff zone, and why is it important in understanding plate tectonics?

Planar zone of seismicity corresponding with the down-going slab in a subduction zone. Differential motion along the zone produces numerous earthquakes with deep foci. The deep-focus earthquake along the zone allow seismologists to map the three-dimensional surface of a subducting slab of oceanic crust and mantle. (Wadati-Benioff zone earthquakes develop beneath volcanic island arcs and continental margins above active subduction zones. They can be produced by slip along the subduction thrust fault or slip on faults within the downgoing plate, as a result of bending and extension as the plate is pulled into the mantle.)

Identify possible consequences of rapid groundwater withdrawal. Choose one or more: A. Pore collapse occurs. B. Swamps form. C. A cone of depression forms. D. Wells go dry.

Pore collapse occurs. A cone of depression occurs. Wells go dry. (Rapid removal of groundwater can result in the formation of a cone of depression and an overall reduction in the surface of the water table; this can cause wells to go dry. Rapid removal of groundwater can also result in pore collapse.)

Which of these are characteristics of either porosity or permeability? Choose one or more: A. Permeability is the same thing as secondary porosity. B. Porosity describes the ability of pores to form conduits through the material. C. Porosity is a measure of the amount of the substance composed of empty spaces. D. Permeability is a measure of how well the pores are connected.

Porosity is a measure of the amount of the substance composed of empty spaces. Permeability is a measure of how well the pores are connected. (Porosity describes the proportion of rock or sediment volume made up of pores (empty spaces), whereas permeability is a measure of the connectedness of pores and the ability of these pores (and fractures) to form conduits through the material. Muddy sediments and fine-grained rock, such as shale or mudstone, may have abundant pore space, but the pores are tiny and poorly connected. Therefore, it is difficult for a liquid to flow through these materials, which are considered to be aquitards (rock or sediment of very low permeability).

* Compare and contrast porosity and permeability.

Porosity: % by volume that is pore space -Primary porosity depends on: o Shape of grains o Arrangement of grains o Size distribution o Compaction/cementation Permeability: the ability of an Earth material to transmit water o Depends on porosity o Degree and size of interconnecting pores between larger pores

Be able to identify how we predict volcanoes. -What are the warning signs we look for to say that an eruption is imminent?

Predicting Volcanic Hazards -Warning signs precede most eruptions o Earthquake activity - Magma flow increases seismicity o Heat flow - Magma causes volcanoes to "heat-up." o Changes in shape - Magma causes expansion o Emission increases - Changes in gas mix and volume -These signs indicate that an eruption is imminent -They cannot predict the exact timing or style

Rodinia and Pangea are supercontinents that assembled during the ______ and _____, respectively. a) Hadean and Archean b) Archean and Proterozoic c) Proterozoic and Paleozoic d) Paleozoic and Mesozoic

Proterozoic and Paleozoic

Describe some of the major volcanic hazards, and explain how they develop. Ash fall Gas Emissions Blocks & Bombs Lava Flow A'a Pahoehoe Pyroclatic Cloud Lahar Landslide

Pyroclastics -Ash (rock name: tuff) ♣ Volcanic glass shards -Lapilli (2-64mm) (rock name: tuff) -Blocks and bombs (rock name: Volcanic Breccia) -Tephra - loose ash or lapilli that has settled to the ground -Pyroclastic Flows (nuee ardentes) ♣ Avalanches of hot ash that race downslope ♣ Moving up to 200 mph, they incinerate all in their path ♣ Immediately deadly; they kill everything quickly ♣ Many famous examples: Vesuvius, Mt. Pelee, Augustine Pyroclastic Flows - aak nuee ardente -Clouds of roiling ash and gas that race downslope -Ride over a carper of superheated air ♣ Eases passage of the flow ♣ Permits high velocities o Immediately deadly to any living thing Volcanic Gases -Gases: carbon dioxide, hydrogen sulfide, sulfur dioxide Acids: hydrogen chloride, sulfuric acid, hydrofluoric acid/hydrogen fluoride Mafic (aka Basaltic) ♣ Basalt flows are often thin and fluid. -They can flow rapidly (up to 100km/hr) -They can flow for long distances (up to several hundred km) -Pahoehoe = glassy, ropy texture -A'a = jagged, sharp, angular texture Lava flows - Lava threats are mostly from basalt -Lava may completely destroy immovable objects o It is rare for lava flows to kill people ♣ Usually there is enough notice ♣ Lava rarely moves faster than people ♣ Sometimes people watching lava flows are killed Tephra - Ash and lapilli fall around the volcano -Can completely bury landscapes, killing plants and crops -Tephra is heavy; it causes roof collapses -Tephra is gritty; it abrades car and airplane engines -Floodwaters easily move tephra as deadly lahars Lahars o Tephra is readily moved by water as a debris flow ♣ Lahars move rapidly (up to 50km/hr) ♣ They have the consistency of wet cement ♣ A distinct hazard to people living in volcanic valleys. Landslides - Eruption-related slope failures. -Eruptions can trigger landslides ♣ Large masses of material are deposited rapidly near vent. ♣ Earthquakes initiate failure of unstable slopes. -Mt. St. Helens ♣ The eruption immediately followed a 3km slope failure ♣ Slide material moved more than 20 km from the peak

A sedimentary rock contains quartz, clay minerals, and iron oxides but no other silicate minerals. It is later metamorphosed without any change in whole rock chemistry, but now possesses garnet crystals. How is this possible?

Recrystallization solid-state recrystallization is a metamorphic process that occurs under situations of intense temperature and pressure where grains, atoms or molecules of a rock or mineral are packed closer together, creating a new crystal structure.

Be able to differentiate among active, dormant, and extinct volcanoes.

Recurrence interval - Average between eruptions o Active - Erupting, recently erupted or likely to erupt o Dormant - Volcano that has no erupted in hundreds to thousands of years (but could still do so) o Extinct - No longer capable of erupting Tectonic changes can shut off the magma "fuel" After extinction, erosion takes over.

How do we distinguish between active, dormant, and extinct volcanoes?

Compare and contrast contact metamorphism and regional metamorphism.

Regional Metamorphism -Tectonic collisions deform huge "mobile belts." -Directed compression thickens mountains. ---> Rocks caught up in mountain buildings are... • Heated via the geothermal gradient and plutonic intrusions • Squeezed and heated by deep burial • Smashed and sheared by differential stresses ---> Convergent boundaries -Regional metamorphism creates foliated rocks -This type of metamorphism is, by far, the most important in terms of the amount of rock altered Thermal (Contact) Metamorphism o Grades of alteration form bands around the pluton ♣ Bands range from highly altered to slightly altered. ♣ Analogous to changes in pottery with increased ??? • Ex. Clay Brick Pottery Porcelain

Describe the changes (deformation) that rocks undergo in orogenic (mountain) belts.

Rocks caught up in mountain buildings are... • Heated via the geothermal gradient and plutonic intrusions • Squeezed and heated by deep burial • Smashed and sheared by differential stresses

What information is needed to locate the epicenter of an earthquake? Why do you need data from a minimum of THREE seismic stations? What is the S-P interval?

S-P interval Data from at least 3 seismic stations 1 station: Epicenter could be at any point on the circle 2 stations: Could be at either of the two points that intersect S-P interval: the time interval between the first arrivals of transverse (S) and longitudinal (P) waves, which is proportional to the distance from the earthquake source.

Be able to discuss how water (fresh & salt) is distributed and stored on Earth. -Where is the fresh water on Earth stored?

Salt water 97% Freshwater 3% Of that 3%... 68.7% Icecaps and Glaciers 30.1% Groundwater 0.9% Other 0.3% Surface water Of that 0.3%... 87% Lakes 11% Swamps 2% Rivers

Be able to explain the differences between seasonal and flash floods. - How does urbanization impact flash flooding?

Seasonal o When torrential rains dump large volumes of water quickly. o After soil pores have been filled by prior rainfalls. Flash o When abrupt warm weather rapidly melts winter snow. o When a natural or artificial dam breaks, releasing water. Urbanization & Floods o Cities cover large areas with impermeable surfaces o Storm water runoff from cities is distinctive ♣ Shorter lag time between rainfall and flood flow ♣ Larger discharges for shorter durations

Why are geologists not able to date sedimentary rocks directly? Choose one: A. Sedimentary rocks are older than their composite minerals. B. Sedimentary rocks are younger than their composite minerals. C. Sedimentary rocks are too fine-grained to accurately date. D. Sedimentary rocks are too coarse-grained to accurately date.

Sedimentary rocks are younger than their composite minerals. (Isotopic dating provides the ages of minerals (grains or crystals) within a rock. Igneous rocks form at the same time as their composite minerals and thus are datable. Sedimentary rock grains, such as sand, mud, and gravel, are derived from the physical and chemical weathering of preexisting rocks at relatively low temperatures. The mineral components within sedimentary rocks are generally much older than the rocks themselves (principle of inclusions).

How is the depth of hypocenter related to plate tectonic setting? How does the depth of the hypocenter influence the amount of damage caused by an earthquake?

Shallow: rupturing at fault lines (transform boundaries) Intermediate or Deep: Subduction zones More shallow --> More damage

Likely consequences of shear stress versus uniform pressure on rocks.

Shear stress: Elongation of grains Foliation Uniform pressure: Development of large, equant grains Rounding of grains

How does slate differ from phyllite? How does phyllite differ from schist? How does schist differ from gneiss?

Slate -Fine clay, low-grade metamorphic shale. -Has a distinct foliation called slaty cleavage. ---> Develops by parallel alignment of platy clay minerals. ---> Slaty cleavage oriented perpendicular to compression. ---> Slate breaks along this foliation, creating flat sheets. Phyllite -Fine mica-rich rock. -Formed by low-medium grade alteration of slate. -Clay minerals neocrystallize into tiny micas. -Micas reflect a satiny luster, -Phyllite is between shale and schist. Schist -Fine-coarse rock with larger micas. -Medium to high-grade metamorphism. -Has a distinct foliation called schistosity. ---> Parallel alignment of large mica crystals. ---> Micas are visible because they have grown at higher T. -Schist often has other minerals due to Neocrystallization. ---> Quartz, Feldspars, Kyanite, & Garnets Gneiss -Has a distinct banded foliation -Light bands of felsic minerals (quartz and feldspars)

Compare and contrast the following metamorphic rocks:. Slate and Schist Marble and Quartzite

Slate -Fine clay, low-grade metamorphic shale. -Has a distinct foliation called slaty cleavage. ♣ Develops by parallel alignment of platy clay minerals. ♣ Slaty cleavage oriented perpendicular to compression. ♣ Slate breaks along this foliation, creating flat sheets. Schist -Fine-coarse rock with larger micas. -Medium to high-grade metamorphism. -Has a distinct foliation called schistosity. ♣ Parallel alignment of large mica crystals. ♣ Micas are visible because they have grown at higher T. -Schist often has other minerals due to Neocrystallization. ♣ Quartz, Feldspars, Kyanite, & Garnets Quartzite -Almost pure quartz in composition -Forms by alteration of quartz sandstone -Sand grains in protolith recrystallize and fuse. -Like quartz, it is hard, glassy, and resistant. Marble -Forms from a limestone or dolostone protolith -Extensive recrystallization completely changes the rock. -Original textures and fossils in parent are obliterated.

Which of the following conditions will tend to make rocks change by ductile deformation rather than by brittle deformation? A. cool surroundings B. granitic composition C. position fairly close to Earth's surface D. slowly applied stress

Slowly applied stress (The only choice that would tend to cause ductile deformation rather than brittle deformation is a slowly applied stress (a slow deformation rate).

Differentiate between stress and strain

Strain -Changes in shape caused by deformation Stress is the force applied across an area -A large force per area result in much deformation -A small force per area results in little deformation -(ex. one person smashing one can versus a person walking across a sheet of cans) 3 Types of Stress -Compression ---> Convergent boundaries ---> Continental collision -Tension ---> Divergent boundaries ---> Continental rift -Shear ---> Strike-slip fault lines ---> San Andreas Fault Stress vs. Strain • Active tectonics put rocks under stress which can lead to deformation • Stress: A measure of the amount of force applied over a given area • Strain: The amount of deformation (distortion) that an object experiences compared to its original size and shape

Which statement is TRUE? Choose one: A. Water from trunk streams flows into tributaries. B. Water travels at the same velocity along the reach of the stream. C. Smooth-bottomed streams often have considerable turbulence. D. Stream flow is fastest in the center of the channel near the surface.

Stream flow is fastest in the center of the channel near the surface. (Water does not travel at the same velocity within a stream because of friction and turbulence; tributaries flow into the trunk stream, and obstacles in rough-bottomed streams, like boulders, create turbulence.)

How do the factors below impact how a rock will behave (ductile or brittle)? Temperature Pressure Rate of Applied Stress Rock Type

Temperature: Hot rocks are more ductile than cool rocks Pressure: Rocks under high pressure are more ductile Rate of Applied Stress: Sudden changes will result in brittle behavior Rock Type:

Which of the following correctly describe the Earth during the Hadean Eon? A. Temperatures were likely too hot to sustain a liquid ocean. B. Its interior was so hot that a solid outer crust, if present at all, was likely being extensively remelted. C. The crust was mostly ultramafic magma and rock, and the atmosphere was dominated by volcanically emitted gases. D. Stable continental interiors first formed. E. It contained abundant deposits of strata with shelly fossils. F. The dinosaurs appeared and came to dominate large-scale terrestrial life.

Temperatures were likely too hot to sustain a liquid ocean. Its interior was so hot that a solid outer crust, if present at all, was likely being extensively remelted. The crust was mostly ultramafic magma and rock, and the atmosphere was dominated by volcanically emitted gases. (This period in Earth's history was marked by a crust of ultramafic magma and rock, which may have been subject to remelting. The atmosphere would have been dominated by volcanically emitted water vapor, nitrogen, and carbon dioxide. For at least part of this eon, a liquid ocean would not have been able to exist.)

Describe the conditions of the crust, atmosphere, and oceans during the Hadean Eon (early Earth)

The crust was predominantly ultramafic magma and rock (which was probably subjected to remelting). ▪The atmosphere lacked free oxygen and would have been dominated by volcanically emitted gases (Carbon dioxide, sulfur dioxide, nitrogen, & water vapor). ▪ For at least the first ¾ of the Hadean, temperatures would have been to HOT to sustain a liquid ocean

Which statements are true of phase changes? A. The crystal structure of the mineral changes. B. The species of mineral changes. C. The atoms in the mineral are rearranged or displaced. D. The chemical composition of the mineral changes

The crystal structure of the mineral changes. The species of mineral changes. The atoms in the mineral are rearranged or displaced.

Which of the following are correct? Choose one or more: A. The smaller the S-P value is, the farther the seismometer is located from the epicenter. B. The longer the S- and P-waves travel, the farther apart their wave fronts are in kilometers. C. The larger the S-P value is, the farther the seismometer is located from the epicenter. D. The shorter the time interval is between the arrival of the S- and the P-waves, the farther the seismometer is from the epicenter. E. The farther the epicenter is, the greater the time difference in the arrival of the P- and S-waves at a seismometer.

The longer the S- and P-waves travel, the farther apart their wave fronts are in kilometers. The larger the S-P value is, the farther the seismometer is located from the epicenter. The farther the epicenter is, the greater the time difference in the arrival of the P- and S-waves at a seismometer. (The longer the waves have traveled in both time and space, the greater the S-P values are.)

Be able to define orogenesis.

The process of mountain formation by deformation of the Earth's crust.

How does the rate of groundwater flow compare with that of ocean currents or river currents? Choose one: A. The rate of groundwater flow is about the same speed as that of surface-water currents. B. The rate of groundwater flow is slower than that of surface-water currents. C. The rate of groundwater flow is faster than that of surface-water currents. D. The rate of groundwater flow can be faster or slower than that of surface-water currents, depending on conditions.

The rate of groundwater flow is slower than that of surface-water currents.

Identify the FALSE statement. Choose one: A. A 200-year flood has a recurrence interval of, on the average, once every 200 years. B. The size of a flood is described in terms of its discharge, measured in cubic feet (or cubic meters) per second. C. An annual probability of 4% means there's a one-in-25 chance that a flood of some given size will happen in any given year. D. The size of a flood and its recurrence interval are inversely related; the larger the flood, the shorter its recurrence interval.

The size of a flood and its recurrence interval are inversely related; the larger the flood, the shorter its recurrence interval. (It's a direct, not inverse, relationship. The larger the flood, the greater the time between recurrences. In other words, smaller floods happen frequently, but very large floods are rare.)

Which of the following is NOT a line of evidence that supports the assertion of global warming, especially over the past 30 years? Choose one: A. Large ice shelves, such as the Larsen B in Antarctica, are breaking up. B. Sea ice has decreased substantially, at a rate of ~3% per decade. C. The spatial area of permafrost regions in low latitudes has substantially increased. D. The rate of ice loss on the Greenland ice sheet has increased.

The spatial area of permafrost regions in low latitudes has substantially increased. (Permafrost regions are decreasing, especially at high latitudes. )

Which of the following statements have NOT been asserted by Intergovernmental Panel on Climate Change (IPCC) reports? Choose one: A. It is extremely likely that human activity has contributed significantly to global climate change. B. Sea level is rising. C. The warming trends observed in the past 50 years can be explained by natural forcing such as cosmic ray flux. D. Earth's climate system is warming.

The warming trends observed in the past 50 years can be explained by natural forcing such as cosmic ray flux.

Select statements true of unconformities. A. There are three major types of unconformities. B. Unconformities represent periods of nondeposition in the rock record. C. Unconformities represent periods of erosion in the rock record. D. Unconformities represent periods of active deposition in the rock record.

There are three major types of unconformities. Unconformities represent periods of nondeposition in the rock record. Unconformities represent periods of erosion in the rock record.

What can banded iron formations tell us about atmospheric oxygen levels?

There was enough oxygen to combine w/ abundant iron in oceans

Which major climatic and biologic events happened during the Pleistocene Epoch? A. There was an increase in dinosaur species and new forms of plant life. B. There were numerous extinctions of large animals toward the end of a glaciation. C. The present-day continents of Asia and Europe collided to create the Himalayas. D. A large meteorite impact drastically reduced the population in the southern hemisphere. E. Much of the northern hemisphere experienced an ice age.

There were numerous extinctions of large animals toward the end of a glaciation. Much of the northern hemisphere experienced an ice age.

Which statements are true about synclines? A. They form from compressional stress. B. They have an arch-like shape. C. They are the result of ductile deformation. D. The limbs dip toward the hinge.

They form from compressional stress. They are the result of ductile deformation. The limbs dip toward the hinge. (Synclines are the result of ductile deformation in response to compressional stress. They have a trough-like shape in which the limbs dip toward the hinge.)

Be able to model Earth's energy flow and budget, both qualitatively and quantitatively • How does insolation change according to latitudinal location? • Be able to identify the dominate climatic zones on the Earth.

Tropics o Generally warm throughout the year o Between Tropics of Capricorn and Cancer Temperate o Between 23.5 and 66.5 North and South o Mild temperatures Polar o 66.5 North and South to the Poles o Cold temperatures

Be able to define what an unconformity is and how they form. You should also be able to distinguish between the 3 types of unconformities: Disconformity, Nonconformity, and Angular Unconformity.

Unconformity: a contact between two rock units in which the upper unit is usually much younger than the lower unit; Unconformities are typically buried erosional surfaces that represent a break in the geologic record of hundreds of millions of years or more (due to erosion/a period of nondeposition). Disconformity: Erosional contacts that are parallel to the bedding planes of the upper and lower rock units. Nonconformity: A contact that separates a younger sedimentary rock unit from an ignenous intrusive rock or metamorphic rock unit. Angular Unconformity: A contact that separates a younger, gently dipping rock unit from older underlying rocks that are tilted or deformed layered rock. Generally represent a longer time hiatus than disconformities because underlying rock had usually been metamorphosed, uplifted and eroded before the upper rock unit was deposited.

Be able to describe how the velocity of a stream varies according to the shape and depth of the channel. - Broad, shallow stream vs a narrow deep stream

Velocity is not uniform in all areas of a channel o Friction slows water along channel edges. Friction is... ♣ Greater in wider, shallower streams ♣ Lesser in narrower, deeper streams o In straight channels, highest velocity is in the center o Few natural channels are straight Water within a stream channel moves at different velocities, creating cut banks (higher velocity) and point bars (lower velocity)

Be able to describe how a meander forms (where is water moving the fastest) and how a stream's sinuosity increases over time. -Compare and contrast a cut-bank and point bar?

Velocity is not uniform in all areas of a channel o Friction slows water along channel edges. Friction is... ♣ Greater in wider, shallower streams ♣ Lesser in narrower, deeper streams o In straight channels, highest velocity is in the center o Few natural channels are straight • Water within a stream channel moves at different velocities, creating cut banks (higher velocity) and point bars (lower velocity)

Be able to identify the dominate tectonic setting(s) of each type of volcano. -Know an example of each type of volcano.

Volcanic types are linked at tectonic settings: -Hot spots - where mantle plumes cut the lithosphere ♣ Oceanic hot spots ♣ Continental hot spots and flood basalts -MORs - spreading axes -Convergent boundaries - Subduction zones ♣ Island Arc Volcanoes ♣ Continental Arc Volcanoes -Continental Rifts Ocean Hot Spots o Plume under an oceanic plate ♣ Basalt erupts at the seafloor and forms a growing mound ♣ A volcano builds above sea level to form an island ♣ Then basalt will not quench and can flow long distances ♣ Lava builds upward and outward and the island grows Continental Hot Spots o Cuts a continental plate ♣ Often erupts both basaltic and rhyolitic material. ♣ Basaltic - Makes up the mantle plume • Rhyolitic - Basalt melts the granitic crust it passes through ♣ Yellowstone - Eruption 640ka created a 100km caldera • 1000 times more powerful than Mt. St. Helens • Deposited 10s of m of ignimbrites • Magma beneath the caldera still fuels geysers • Heads a hot spot track MOR Eruptions o Most lava erupts along the mid-ocean ridge (MOR) o MOR-produced oceanic crust covers 70% of Earth o Basalt erupted from fissures quenches as pillows Convergent Boundaries o Most subaerial volcanoes form at convergent boundaries ♣ Volatiles from subducting plate initiate melting. ♣ Arc volcanoes develop on overriding plate • May cut through oceanic or continental crus o The "Ring of Fire" dominates Pacific margin Continental Rifts o Yield an array of volcano types reflecting... ♣ Partial melting of the mantle (mafic magmas) ♣ Partial melting of the crust (Felsic magmas) o Examples: ♣ East African Rift ♣ Basin and Range ♣ Mid-continent Rift

How do geologists predict volcanic eruptions?

Warning signs precede most eruptions o Earthquake activity - Magma flow increases seismicity o Heat flow - Magma causes volcanoes to "heat-up." o Changes in shape - Magma causes expansion o Emission increases - Changes in gas mix and volume These signs indicate that an eruption is imminent They cannot predict the exact timing or style

Be able to discuss ways that humans mitigate earthquake damages

We can't stop them but we can be ready for them. o Understand what happens during an earthquake o Map active faults and areas likely to liquefy from shaking o Train the community in earthquake preparedness o Run preparedness drills o Educate individuals on safe behavior and responses

Be able to define isostacy and explain how isostatic equilibrium reached.

What is Isostasy? -Surface elevation represents a balance between forces o Gravitational attraction - Pushes plate into the mantle o Buoyancy - Causes plate to float higher on the mantle -The term isostatic equilibrium describes this balance. -Isostasy is compensated after a disturbance. o Adding weight pushes the lithosphere down. o Removing weight causes the isostatic rebound. -Compensation is slow, requiring asthenospheric flow.

How does the elastic-rebound theory explain the occurrence of earthquakes? Choose one: A. The bending motion of crustal rocks causes the surrounding crust to vibrate as earthquakes. B. Colliding rocks cause kinetic energy to travel through the crust in the form of earthquakes. C. When bending rocks fail, tension energy is released in the form of earthquakes. D. When bending rocks fail, stress energy is released in the form of earthquakes.

When bending rocks fail, stress energy is released in the form of earthquakes. (When stress is applied to rock at a fault zone, and friction inhibits the rocks on opposite sides of the fault from sliding past one another, rock is deformed and stores energy produced by the stress. Ultimately, the rock will fail under stress, elastically returning to its prior shape and producing sudden slip along the fault plane. The release of this deformational energy produces the vibrational waves we sense as an earthquake.)

What is a mass extinction?

Widespread and rapid decrease in biodiversity on Earth thought to be due to factors such as a catastrophic global event or widespread environmental change

A Wadati-Benioff zone is Choose one: A. an area where continents collide following the subduction of the lithosphere. B. an area in a divergent boundary where new lithosphere forms. C. a series of strike-slip faults along a transform boundary. D. a band of earthquakes along subducting lithosphere in a convergent boundary.

a band of earthquakes along subducting lithosphere in a convergent boundary. (The Wadati-Benioff zone is an oblique band of earthquake foci that descends into the mantle along with the subducted lithospheric slab, extending to a depth of 670 km. Because the mantle rocks at this depth are too hot and weak to experience earthquakes, the occurrence of earthquake activity proves that the surficial lithosphere is indeed subducted into Earth's interior, clearing the way for new lithosphere to be produced along either side of mid-ocean ridges.)

Which of the following is NOT considered a warning sign of imminent eruption? Choose one: A. change in heat flow from the volcano's surface B. increase in gas emissions and hydrothermal activities C. earthquake activity D. a period of quiescence in the volcano's activity

a period of quiescence in the volcano's activity

The presence of pillow lava is evidence of what volcanic circumstance? Choose one: A. a submarine volcano B. an explosive eruption C. caldera formation D. high-silica-content magma

a submarine volcano (Pillow lava is a low-silica-content, basaltic lava associated with underwater effusive eruptions.)

Identify the FALSE statement. Volcanic gases A. are not harmful because most are less dense than air. B. are more abundant in felsic lavas than mafic lavas. C. killed over 1,700 people at Lake Nyos, Cameroon, Africa, in 1986. D. are released by magma as it rises and the pressure decreases

are not harmful because most are less dense than air. (Volcanic gases include water vapor, carbon dioxide, sulfur dioxide, and hydrogen sulfide. Some, including carbon dioxide, are more dense than air. Regardless of the density of the gases, volcanic gases can be extremely harmful.)

Mt. Vesuvius erupted in a very violent explosion in 79 CE and buried the residents of Pompeii in ash. On the basis of this information, which of the following would you LEAST expect to find at Vesuvius? A. basaltic lava B. lapilli (cinders) C. ignimbrite D. rhyolite lava

basaltic lava (Basaltic lava is associated with nonviolent, effusive eruptions; rhyolite lava and lapilli and ignimbrite (all pyroclastic products) indicate a rock chemistry that results in explosive eruptions.)

Which statement is FALSE? Liquefaction Choose one: A. can cause sediment to turn into an unstable slurry incapable of supporting weight. B. can cause roads, fences, and pipelines to crack and separate if they straddle a fault. C. increases the pressure of the water that fills the pore space between sediment grains. D. can affect sand layers below ground surface and cause them to erupt as sand volcanoes or sand boils.

can cause roads, fences, and pipelines to crack and separate if they straddle a fault. (Shaking and displacement cause linear features, such as roads, fences, and pipes, to crack and separate across faults, not liquefaction.)

The Cambrian explosion not only produced an abundance of new animals species, but also gave rise to the first shells, spines, and active swimmers. The suggest the importance of ________ in driving animal evolution. a) photosynthetic organisms b) atmospheric oxygen c) carnivorous predators d) filter-feeding organisms

carnivorous predators

Which of the following is a method of removing carbon dioxide from the atmosphere? Choose one: A. dissolution of rocks B. decay of dead animals C. chemical weathering of rocks D. metamorphism of rocks

chemical weathering of rocks

What life-forms appeared during the Mesozoic Era? A. spiders, scorpions, insects, and crustaceans in both dry-land and freshwater habitats B. dinosaurs, mammals, birds, large swimming reptiles, and pterosaurs C. swampy forests with tree-sized relatives of club mosses and ferns D. trilobites, mollusks, brachiopods, nautiloids, gastropods, and graptolites

dinosaurs, mammals, birds, large swimming reptiles, and pterosaurs (Along with dinosaurs, swimming reptiles, and pterosaurs, the first feathered birds and the earliest ancestors of mammals also appeared.)

What are some of the sources of water in streams? Choose one or more: A. direct rainfall B. inflow from tributaries C. runoff from surrounding lands D. backwash from the ocean E. groundwater discharge

direct rainfall inflow from tributaries runoff from surrounding lands groundwater discharge (Streams conduct water from elevated regions of a landmass down to the sea. Sources of water in streams include direct rainfall, runoff from the surrounding land, inflow from tributaries, and groundwater discharge.)

Geologists study Earth's climate history by deciphering clues preserved in the geologic record. In the northern hemisphere, which of the following observations would you expect to see if the climate were colder in the geologic past than it is today? Choose one or more: A. a more northerly distribution of spruce forests B. higher 18O/16O ratios in plankton shells C. a more southerly distribution of spruce forests D. grass pollen being more abundant than spruce pollen E. spruce pollen being more abundant than grass pollen F. lower 18O/16O ratios in plankton shells

higher 18O/16O ratios in plankton shells a more southerly distribution of spruce forests spruce pollen being more abundant than grass pollen (When glaciers expanded during the last ice age, spruce forests of the northern hemisphere migrated farther south. When large glaciers are forming, a great deal of 16O is removed from the ocean, causing the water that remains to become enriched in 18O and thus creating a higher 18O/16O ratio. During times of glaciation, plankton make their shells out of calcium carbonate (CaCO3) using the ocean water with a higher 18O/16O ratio.)

A typical longitudinal profile of a stream Choose one: A. illustrates that a stream's gradient is steeper near its headwaters than near its mouth. B. is roughly a convex-upward curve. C. shows almost horizontal plains near the stream's headwaters, and deep valleys near its mouth. D. shows a cross section of the stream from bank to bank at one particular site.

illustrates that a stream's gradient is steeper near its headwaters than near its mouth. (A profile shows the cross section along the stream's entire length; the curve is concave-up; the profile shows horizontal plains near the mouth, deep valleys near the headwaters.)

Identify the FALSE statement. Floods can occur Choose one: A. in any area, but flash floods are most unexpected in humid regions. B. if saturated ground receives additional rainfall. C. when a watershed receives more water than it can absorb or evaporate. D. after a dam or levee breaks, creating a flash flood.

in any area, but flash floods are most unexpected in humid regions. (Flash floods are most unexpected in arid regions, where channels that have not received a drop of rain are suddenly filled by an isolated thunderstorm.)

An ephemeral stream Choose one: A. in dry climates may sometimes become a dry wash (also called wadi or arroyo). B. is replenished by both precipitation and groundwater. C. flows year-round. D. is one whose bed lies below the water table.

in dry climates may sometimes become a dry wash (also called wadi or arroyo).

Identify the FALSE statement. A drainage network Choose one: A. is considered a trellis network when rivers flow over uniform substrate with gentle slope. B. collects water over a large area. C. is an interconnected group of streams. D. drains water toward the ocean.

is considered a trellis network when rivers flow over uniform substrate with gentle slope. (A drainage network is a collecting basin for area precipitation and a series of channels to conduct the water out of the area and toward the sea, but a trellis drainage network does not form over uniform substrate with gentle slope (that would create a dendritic network).

Which of the following statements is FALSE? The water table Choose one: A. lies within a few meters of the surface in arid areas. B. may be defined by the surface of a permanent stream, lake, or marsh. C. mimics the topography of the land it underlies. D. becomes a downward-pointing cone-shaped surface around the bottom of a well.

lies within a few meters of the surface in arid areas. (In arid regions, the water table may be hundreds of meters below the ground surface.)

Groundwater contaminants Choose one: A. like methane, arsenic, and salt may occur naturally in groundwater. B. are all eventually removed by rock and sediment acting as natural filters. C. dissipate quickly into the groundwater reservoir and often do not pose a problem. D. are always toxic materials like arsenic, mercury, and lead.

like methane, arsenic, and salt may occur naturally in groundwater. (Contaminants in groundwater often remain in a contaminant plume and travel far from the source, can't all be naturally filtered out, and can be nontoxic materials like salt, iron, lime, and sulfur.)

Identify the FALSE statement. The Richter scale Choose one: A. measures the size of a quake in terms of the damage it does (its intensity). B. is today termed a local magnitude reading (ML). C. measures the amplitude of the largest deflection on a seismogram in response to specifically defined seismic waves at a specifically defined distance and depth. D. works well only for shallow, nearby earthquakes.

measures the size of a quake in terms of the damage it does (its intensity). (The Richter scale measures quake size in terms of the ground motion it generates (its magnitude). The Modified Mercalli Intensity (MMI) scale measures the size of an earthquake in terms of the damage it does (its intensity).

Which of the following are methods used by geologists to predict a volcanic eruption? A. measuring an increase in heat flow B. observing changes in the shape of a volcano C. measuring an increased occurrence of gaseous emissions D. measuring a decrease in gas and steam emissions E. measuring an increased incidence of earthquakes

measuring an increase in heat flow observing changes in the shape of a volcano measuring an increased occurrence of gaseous emissions measuring an increased incidence of earthquakes

Fluvial landscapes that are early in their evolutionary progression have Choose one: A. natural levees. B. narrow, deep valleys. C. broad floodplains. D. oxbow lakes.

narrow, deep valleys

Which gas found today in Earth's atmosphere was absent in the Hadean's and Archean's? a) nitrogen b) water vapor c) oxygen d) carbon dioxide

oxygen

Oxygen in Earth's atmosphere is derived from: a) volcanic outgassing b) photosynthesis c) animal respiration d) water from the oceans breaking down into hydrogen and oxygen during evaporation

photosynthesis

Long-term earthquake predictions are based on which of the following? Choose one or more: A. foreshocks B. earthquake magnitude C. recurrence intervals D. seismic belts

recurrence intervals seismic belts (Long-term earthquake predictions are on the basis of recorded earthquake occurrences. Within a designated time span, higher probabilities of future earthquakes are assigned to regions that have historically been seismically active. More specifically, within belts of seismicity, seismic gaps may be "due" for an earthquake. Smaller earthquakes will occur more frequently than large earthquakes in any one particular region.)

Which of the following statements is TRUE? Earthquakes in California are Choose one: A. the result of reverse faulting along the San Andreas fault. B. shallow and occur in the upper 15 km of crust, even though the San Andreas fault cuts through the crust to deeper depths. C. the result of widening along the San Andreas fault, which will eventually cause western California to sink into the ocean. D. always above magnitude 7.5 because the San Andreas is such a large fault.

shallow and occur in the upper 15 km of crust, even though the San Andreas fault cuts through the crust to deeper depths. (Quakes in California can be large or small and occur along hundreds of faults. Motion along the San Andreas fault is strike slip, and it's not causing the state to sink. The San Andreas fault sits on a transform boundary, but because movement at depth is plastic, earthquakes usually occur in the upper 15 km.)

Toward the end of the Archean eon, ___ a) the first abundant shelly organisms appear in the fossil record b) Earth's interior was so hot that a solid outer crust, if present, was likely being extensively remelted c) stable continental interiors, termed cratons, first formed d) the dinosaurs appeared and came to dominate large-scale terrestrial life

stable continental interiors, termed cratons, first formed

Which of the following are the primary gases that erupt from volcanoes? A. oxygen B. sulfur dioxide C. carbon dioxide D. carbon monoxide E. water vapor F. hydrogen sulfide

sulfur dioxide carbon dioxide water vapor hydrogen sulfide

Which of the following does NOT contribute to long-term climate change? Choose one: A. position of the continents B. tectonic uplift C. the evolution of certain life-forms, such as photosynthetic organisms D. sunspot activity

sunspot activity (Sunspot activity contributes to short-term climate change, rather than long-term.)

The Mesozoic is a time in Earth history when... a) the first abundant shelly organisms appear in the fossil record b) Earth's interior was so hot that a solid outer crust, if present, was likely being extensively remelted c) stable continental interiors, termed cratons, first formed d) the dinosaurs appeared and came to dominate large-scale terrestrial life

the dinosaurs appeared and came to dominate large-scale terrestrial life

The Cambrian is a time in Earth history when... a) the first abundant shelly organisms appear in the fossil record b) Earth's interior was so hot that a solid outer crust, if present, was likely being extensively remelted c) stable continental interiors, termed cratons, first formed d) the dinosaurs appeared and came to dominate large-scale terrestrial life

the first abundant shelly organisms appear in the fossil record

An iridium-rich layer of clay, glass spherules, and shocked quartz grains strongly suggest that the K-T boundary extinctions were at least in part caused by: a) a long trend of global warming b) a long trend of global cooling c) worldwide explosive volcanism d) the impact of a bolide (meteoroid or comet)

the impact of a bolide (meteoroid or comet)

An explosive volcanic eruption does not produce lava flows because A. the lava produced cools too quickly due to the abundant water in the surrounding environment. B. the gases below the surface rise and cause the magma to cool and solidify. C. the overriding plate at the subduction zone where the volcano formed is composed of oceanic lithosphere. D. the sudden release of accumulated gas pressure blasts the lava upward, forming pyroclastic debris.

the sudden release of accumulated gas pressure blasts the lava upward, forming pyroclastic debris.

Groundwater Choose one: A. completely fills the zone of aeration above the water table. B. moves underground mainly in underground river channels. C. dissolves very porous rock like obsidian faster than it dissolves limestone. D. typically moves slowly within the ground through porous rock layers like sandstone.

typically moves slowly within the ground through porous rock layers like sandstone. (The zone of saturation is below the water table; groundwater moves mainly through interconnected pore spaces in rock and sediment, rarely in underground lakes or streams; and unfractured obsidian is neither soluble nor porous.)

Which of the following creates the vesicles in vesicular basalt? Choose one: A. rapid cooling of a lava by water B. slow cooling within the magma chamber in the presence of water C. high silica content in the lava D. volatiles that escape from lava during an eruption

volatiles that escape from lava during an eruption (Vesicles are frozen bubbles within lava that form as gases depressurize and are released during eruption.)

Where would you go if you wanted to find exposed metamorphic rocks, and how would such rocks have returned to the surface of Earth after being at depth in the crust?

you can find these metamorphic rocks by going to a mountain range and looking at the towering cliffs in the interior of a mountain range(typically reveals schist, gneiss, and quartzite) exhumation(refers to the overall process by which deeply buried rocks end up back at the surface) HOW IT WORKS: when crust collides, the rock in the middle squeezes upward. Also erosion can cause this

Which of the following does not provide evidence for the great oxygenation event? A. deposition of banded iron formations B. zircon deposits mixed with quartz C. the age of redbeds D. clastic grains of pyrite in sandstones

zircon deposits mixed with quartz (The oxygen newly added to the atmosphere allowed seawater to oxidize iron and transform it so that it could not dissolve. As a result, a vast amount of iron precipitated out of the ocean and collected on the seafloor as sediment. Once buried and lithified, it formed banded iron formations. It is not possible to find well-formed iron sulfide (pyrite) in sediment today because it oxidizes in an oxygen-rich atmosphere; thus, it will not last long enough at the surface to become a sedimentary clast. Redbeds, clastic rocks colored by bright-red iron oxide, form only when groundwater rich with oxygen flows through sediment during lithification. These rocks do not appear in the geologic record until after 1.8 Ga, the end of the oxygenation event.)

How does orogenesis lead to the formation of igneous, sedimentary, & metamorphic rocks?

• The weight of the mountain pushes the surface of the crust down to create a basin • Rocks once at great depth are faulted and squeezed up to the surface • Igneous pluton intrudes; contact metamorphism takes place around it

One of the most studied mass extinctions occurred at the K-T Boundary. What could have caused this mass extinction?

▪ Extraterrestrial impact the produced the Chicxulub crater. ▪ Volcanic activity may have induced climatic change or instability.

What are stromatolites, how do they form, and why are they important?

▪ Stromatolites are sedimentary mounds created by the presence of sticky cyanobacteria mats that trap sediment. ▪ They are important, b/c they were the first organisms to effectively photosynthesize.

. How did the atmosphere & tectonic conditions change during the Proterozoic Eon?

▪ The atmosphere became oxygenated (and depleted the high levels of carbon dioxide) as a result of photosynthesis. ▪ Plate tectonic conditions become more similar to what is observed today—with the development of broad, stable cratons in continental interiors.

Be able to identify and explain the relative motion that is associated the normal, reverse, thrust, & strike-slip faults.

♣ Dip-Slip Faults • Sliding is parallel to fault plane dip o Thus, blocks move up or down the slip of the fault • 3 kinds of dip-slip fault depend on relative motion o Normal fault - handing wall moves down ( tension) o Reverse fault - hanging wall moves up ( compression) o Thrust fault - hanging wall moves up at a low angle ( compression) ♣ Strike-Slip Faults • Fault motion is parallel to the strike of the fault. • Classified by the relative sense of motion. To find this... o Imagine standing on one block looking across the fault o Which way does the opposite block move? • Right lateral - Opposite blocks moves to the observer's right • Left-lateral - Opposite block moves to the observer's left

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