All study questions from Unit 3

What are the major divisions of Earth's interior based on chemical composition differences?

The crust, mantle and core.

• the crust is composed mainly of silicates

• the mantle is mostly silicates

• the core is made of iron-nickel alloy

What are the major divisions of Earth's interior based on physical property differences?

• the lithosphere (crust and upper-most solid mantle) is the strong, rigid outer layer of earth

• the asthenosphere (upper mantle) is the “weaker” plastic layer below the lithosphere

• the outer core is liquid

• the inner core is solid

What is a lithospheric plate?

large, rigid segments of Earth’s solid outer shell—comprising the crust and uppermost mantle—that float and move on the hotter, plastic asthenosphere

Do all lithospheric plates move in the same direction?

no, all lithospheric plates do not move in the same direction

What does the motion of lithospheric plates mean for the locations of continents over time?

The motion of lithospheric plates constantly reshapes Earth's surface, causing continents to drift, collide, and break apart over millions of years

What are the different types of plate boundaries?

• divergent boundaries: plates moving apart

• convergent boundaries: plates moving towards each other

• transform boundaries: plates moving past each other

What is the Theory of Plate Tectonics?

The theory of plate tectonics states that Earth's outer shell (lithosphere) is divided into several large, rigid plates that glide over a hotter, plastic-like layer (asthenosphere)

What is the Theory of Plate Tectonics meant to explain?

it is meant to describe how large continents and geologic features form

What evidence supports the Theory of Plate Tectonics?

- Thickness of ocean floor sediments

• sediment thickness increases as you get farther from crest of ocean ridge

- hot spot tracks show accumulation of volcanic activity, and as you move further away from hot spot, the rock ages

- paleomagnetism records left in rock sediment on ocean floor correlate to polarity flips throughout history

Where do most major earthquakes occur?

most major earthquakes are associates with movement along plate boundaries

• convergent plat boundaries produce the strongest earthquakes

• divergent generally do not produce large earthaquakes

What causes most earthquakes?

the movement of rocks along faults within the Earth's crust, driven by the tectonic plate movement

How do we know that an earthquake has occurred?

seismic waves generated with each slippage along a fault and are indicators of an earthquake

What is a seismic wave?

physical waves that travel on the surface or through the interior of planetary bodies

What is a primary difference between body and surface waves?

body waves can travel through planetary bodies but surface waves can only travel on or near the surface of planetary bodies

Do P and S waves travel at the same speed?

No, P waves have the highest velocity so they arrive first, then the S waves are second to arrive (slightly slower)

How are P and S wave arrival times used to determine when and where an earthquake occurred?

the time difference between P and S wave arrivals give the distance to the epicenter. The method of triangulation is then used to pinpoint the location

Do P and S waves travel through all types of materials?

P waves can travel through all materials, while S waves can travel only through solids

How do the differences in materials P and S waves can travel through help us learn about Earth's interior?

By observing that S-waves cannot pass through the outer core (creating a "shadow zone"), scientists confirmed it is liquid.

Are earthquakes common?

yes, though majority are low magnitude. Only a few large magnitude earthquakes per year

What is a seismic gap?

a segment of an active fault zone that has historically produced earthquakes but has remained quiet, experiencing little to no significant seismic activity for a long period

What is the connection between earthquakes and tsunami?

Earthquakes cause a large displacement of ocean water, that leads to a series of large ocean waves

What methods are used to map the ocean floor?

SONAR (uses sound waves)

• single beam and multi-beam receivers

Radar altimetry (uses radio waves)

• “radio detection and ranging”

Lidar altimetry (visible and infrared light)

• “light detection and ranging”

How do plate movements relate to the creation and destruction of ocean floors?

primarily at tectonic plate boundaries. New ocean floor is created at divergent boundaries (mid-ocean ridges) through magma upwelling, while old ocean floor is destroyed at convergent boundaries (subduction zones) where dense plates sink back into the mantle

What is happening at a mid-ocean ridge

tectonic plates diverge, creating new ocean floor through seafloor spreading.

What is happening at an ocean trench?

Deep-sea trenches are steep, narrow depressions marking convergent plate boundaries, where one tectonic plate subducts under another, driving intense volcanic activity (creating island arcs), and generating powerful earthquakes

About how old is the oldest part of the floor of the Atlantic Ocean?

180 mya

Are ocean floors older or younger than continents?

ocean floors are younger than the continents

Does the lithosphere get thinner or thicker as you get farther from a mid-ocean ridge?

The oceanic lithosphere gets thicker as you get farther from a mid-ocean ridge

What type of activity (or lack of activity) is referred to with the terms active margin and passive margin?

Active margins and passive margins refer to the presence or absence of tectonic plate boundary activity at the edge of a continent. Active margins are located at crashing or converging plate boundaries, while passive margins are within plates, far from boundaries

What features are common at an active margin?

they are characterized by high volcanic and earthquake activity

What features are common at a passive margin?

long-term geological stability, thick sediment accumulation, and a distinct lack of significant volcanic or earthquake activity

What is deformation in the geologic sense?

the transformation of rocks from their original size, shape, or position due to applied forces (stress) within the Earth's crust.

What produces deformation?

differential stress (compressional, extensional, and shear)

Do all types of applied stress result in deformation?

yes, all forms of differential stress results in deformation

What distinguishes different types of faults?

Faults are distinguished by the direction of relative movement (slip) between rock blocks and the type of stress applied (tension, compression, or shear). The primary types are normal (extension/downward), reverse (compression/upward), and strike-slip (shear/horizontal), classified by how the hanging wall moves relative to the footwall

What types of geologic structural features in the crust are created by deformation?

Geologic deformation creates structural features like folds, faults, and joints

Which are created by compressional stress?

reverse and thrust faults

Which are created by extensional (tensional) stress?

Normal faults

Which are created by shear stress?

strike slip faults

Why do some rocks break and others bend?

Rocks break (brittle deformation) or bend (ductile deformation) based on temperature, pressure, speed of force, and composition

What are the factors that affect whether a rock experiences brittle or ductile deformation?

• low temp, low pressure, quickly applies pressure, and strong locks with interlocked grains results in brittle deformation

• high temp, high pressure, slowly applied pressure, and weak rocks result in ductile deformation

What is a geologic example of ductile deformation?

A classic geological example of ductile deformation is rock folding, such as anticlines and synclines observed in mountain belts like the Himalayas or Alps

What is a geologic example of brittle deformation?

A key geologic example of brittle deformation is the San Andreas Fault, where rock breaks and shifts under stress, causing earthquakes.

What type of plate boundary (convergent, divergent, transform) is responsible for creating most continental mountains?

Convergent plate boundaries are responsible for creating most major continental mountains

What type of convergent plate boundary is responsible

for the formation of the Himalayan mountains and Appalachian mountains?

continent-continent convergent plates (alpine type mountain building)

What is Exotic Terrane?

a fault-bounded piece of continental or oceanic crust that originated from a distant, foreign location and was transported by tectonic plates to collide and suture onto a new continental landmass. These "displaced" fragments differ significantly in geological history, fossils, and rock type from the surrounding rocks

What is the difference between relative age and absolute age?

Relative age determines if a rock or fossil is older or younger than another based on position (e.g., layers), while absolute age provides a specific numerical age in years

How can relative age be determined?

Relative age is determined by evaluating the order of geologic events—which rock or feature is older or younge

How can absolute age be determined?

through radiometric dating

What age is considered young for a mountain range?

formed within the last 100 million years

What is the Geologic Time Scale?

a chronological system, or "calendar", used by scientists to map the 4.5-billion-year history of Earth.

How old is Earth?

~ 4.54 billion years old

What are the eons in the Geologic Time Scale?

Hadean → Archaean → Proterozoic → Phanerozoic

When (in what eon) did Earth develop an atmosphere?

Hadean Eon

What is the primary difference between the atmosphere today and the earliest atmosphere?

The primary difference between Earth's early atmosphere and today's is the presence of free oxygen (). The early atmosphere was a toxic mix dominated by carbon dioxide, nitrogen, water vapor, and methane with virtually no oxygen, while the modern atmosphere contains oxygen, largely produced by early photosynthetic life

When (in what eon) did Earth develop oceans?

The Hadean eon, outgassed water condenses to form rain

When (in what eon) does evidence of life on Earth first appear?

Archaean eon

Why did the dinosaurs disappear?

K/T boundary extinction caused by asteroid impact on Yucatan peninsula (66 mya)

Was Pangaea the only supercontinent that existed on Earth?

No, others include:

• Nuna (aka columbia) → 2.1 - 1.8 bya)

• Rodina → 1.1 - 0.9 bya

• Pannotia → 0.61 bya

What determines whether a resource is renewable or nonrenewable?

if it can replenish itself in 70 years or less, it is renewable.

• solar power and wind are renewable

• coal, natural gas, and petroleum are non-renewable

Why are some groundwater sources considered renewable and

others are considered nonrenewable?

If humans pump water out faster than nature can replace it, it is functionally nonrenewable.

• some aquifers just replenish faster than others depending on location

Are mineral resources evenly distributed around the world?

no, resources are not evenly distributed worldwide

What are some ways in which mineral resources are concentrated?

• magmatic differentiation (heavy minerals settling in magma),

• hydrothermal solutions (hot, metal-rich fluids filling cracks)

• sedimentary processes (density sorting in water/wind), and

• weathering (leaching away undesired materials)

Are energy resources evenly distributed around the world?

No, energy resources are not evenly distributed around the world

Do geologic settings (or conditions) have any relationship to locations of certain types of energy resource reserves?

• Petroleum and natural gas are predominantly found in sedimentary rocks—such as sandstone and carbonate—that were once shallow marine environments.

• Tectonic movement causes rock to buckle and fold, forming structural traps (like anticlines) that collect migrating oil and gas

• Coal deposits originate from dead organic matter accumulating in swamps, bogs, and marshes (often in fluvial or deltaic environments) that are subsequently buried and subjected to heat and pressure

Why is oil shale not a major source for production of oil today?

because it is not profitable to extract

What is fracking, and what does it produce?

a drilling technique used to extract oil and natural gas from tight underground rock formations, such as shale, by injecting high-pressure water, sand, and chemicals to create cracks

What is a common mechanical objective of different energy sources that are used to produce electricity?

A common mechanical objective across most electricity generation methods—including fossil fuels, nuclear, hydro, and wind—is to drive a turbine to produce rotational mechanical energy

What is meant by global warming?

Global warming is the long-term, human-caused rise in Earth's average surface temperature, driven by greenhouse gases (like and methane) trapping heat in the atmosphere.

What is meant by climate change?

Climate change refers to long-term shifts in temperatures and weather patterns, primarily driven by human activities—especially burning fossil fuels—which increase heat-trapping greenhouse gases in the atmosphere

What is the relationship between global warming and climate change?

global warming eventually leads to climate change

Has the amount of carbon dioxide in the atmosphere changed over time?

yes, it has changed significantly over the history of the earth

How have the levels of CO2 changed over the past 70 years?

Atmospheric levels have risen dramatically over the past 70 years, increasing from just over 300 parts per million (ppm) in the 1950s to over 420 ppm today

How do current CO2 levels compare to levels over the past 800,000 years?

Current atmospheric levels (over 420 ppm in 2024) are higher than at any point in at least the last 800,000 years

How do we know what the carbon dioxide levels were over the

past 800,000 years?

instrumental records such as paleoclimatology, glacial ice analysis, marine growth analysis, and pollen and spore analysis (specifically glacial ice analysis)

What is the greenhouse effect and how does it work?

Earth’s surface reemits absorbed solar energy as infrared light. admitted infrared light gets absorbed by the gases in the atmosphere, which trap them and warms the planet.

Is carbon dioxide the only gas that can create a greenhouse effect?

no, methane, nitrous oxide, and water vapor contribute as well

Is Earth the only place in the Solar System where geologic processes are (or have been) active?

Earth is the only planet in the Solar System with active plate tectonics, but it is not the only place with active geologic processes. Venus, Mars, Mercury, and moons like Io and Europa show evidence of volcanism, tectonism, or surface changes

Are there crustal deformations anywhere besides Earth?

Yes, crustal deformations occur elsewhere in the solar system, though Earth is the only body with active, large-scale plate tectonics.

Does (or did) volcanism occur on other planetary bodies?

the Moon, Venus, Mars, Io, and Enceladus all shows evidence of past volcanism, with Mars housing the largest volcano in the solar system (Olympus Mons), Io being the most volcanically active planetary body in our solar system, and Enceladus having water geysers

Do the processes of erosion, transport and deposition operate on other planetary bodies besides Earth?

• Mars shows past and present evidence of mass movement activity and wind processes, as well as past surface liquid processes

• Titan (moon of Saturn) shows surface liquid processes of seas/lakes of hydrocarbons

On which Solar System bodies are surface liquids stable on the surface today?

Earth and Saturn's largest moon, Titan, are the only bodies in the Solar System known to have stable liquids on their surfaces today

• earth has liquid water

• titan has liquid hydrocarbons