unit 3 geology exam

what characteristics of minerals affect the distance of seismic waves

• density

• elasticity

• mineral composition

• denser and more elastic the mineral, the farther seismic waves can travel through it before dissipating

Earthquake

vibration of Earth produced by the rapid release of energy

Epicenter

location on Earth’s surface that lies directly above the focus of an earthquake

Hypocenter

zone within Earth where rock displacement produces an earthquake

Foreshocks

small earthquakes that often precede a major earthquake

Aftershocks

smaller earthquake that follows the main earthquake

What is a megathrust earthquake and where would you find them?

• Powerful earthquake that occurs at subduction zones, where one tectonic plate is forced beneath another

• occur along convergent plate boundaries

What is a seismometer and what does it record?

• An instrument that detects and measures the vibrations caused by seismic waves during an earthquake

• records intensity, duration, and direction of these ground movements, providing data on the earthquake's strength and location

Compare and contrast the two types of seismic waves (i.e., Body Waves vs Surface Waves), and be sure to provide two examples of each

• body waves travel through the earth

• P waves go though liquid, think slinky, and faster

• S waves do not go through liquid, think garden hose, and 2nd fastest

• surface waves stay on the surface

• they are the slowest waves but have the most shaking

• L waves think back and forth

• R waves think circle motion

Compare and contrast the Mercalli Intensity Scale and Moment Magnitude

• The Mercalli Intensity Scale measures earthquake effects and damage, while the Moment Magnitude Scale measures total energy released.

• Mercalli varies by location, Moment Magnitude provides a single global value.

How does crust type or material affect the propagation of seismic waves?

• Seismic waves travel faster in dense, rigid materials (like rock) and slower in softer materials (like soil).

• Softer materials also absorb more energy, weakening the waves.
  

What types of rocks give us an idea of the original/initial composition of the earth? Why?

• Peridotite and basalts because from the mantle it is carried from the mantle to the Earth’s surface providing clues about the Earth’s interior.

• Meteorites represent the original material from which the Earth and other planets formed
  

What methods do we use to gain information about the structure of the earth? Why?

• Seismic waves, drilling, and magnetic/gravitational field measurements to study Earth’s structure.

• Seismic waves reveal interior layers by how they travel through Earth

• Drilling sample materials directly

• Magnetic and gravitation measurements indicate variations in earth’s composition and density

What is the Moho?

boundary between the Earth's crust and the mantle

By what mechanism is heat transferred from the core to the crust of the planet

• conduction

• convection

What were the two sources of Earth’s original heat?

• accretional heat

• radioactive decay

What seismic evidence tells us the outer core is molten and not solid?

shadow zones

What is the major control on the distribution of earthquakes (globally)?

plate boundaries

What conditions are needed for the outer core to be in a liquid state while the other Earth layers are not? Is the outer core the hottest part of the Earth, since it is molten?

• outer core is liquid due to high temperature and lower pressure

• inner core is hotter but solid due to extreme pressure

how do we know about the interior of the earth? how do we know it is layered?

• volcanic rocks

• meteorites

waves that do not travel through liquid

s waves

how does heat move or energy travel?

• conduction (contact)

• convection (boil)

• radiation

Hydrologic Cycle

movement of water

Watershed/drainage basin

area of land drained by a stream

Headward erosion

extension upslope of the head of a valley due to erosion

Laminar Flow

movement of water particles in straight-line paths that are parallel to the channel

Turbulent Flow

erratic movement of water often characterized by swirling, whirlpool-like eddies

What information does a drainage pattern provide? include 2 examples

• shows how water flows over land and provides clues about the land's structure and rock types

• ex: dendritic and trellis

What factors affect flow velocity?

• channel gradient (slope) [steeper=faster]

• channel shape (cross-sectional area)

• channel size and roughness [rough=slower]

• discharge (amount of water flowing)

Explain how channel shape affects flow velocity?

the less contact the water makes with the banks and bed of a channel, the faster the flow

List and define the three types/groups of sediment transport

• bed load = sediment that rolls, slides, or bounces along riverbed

• suspended load = find particles, like silt and clay, are carried within the water column

• dissolved load = soluble materials, such as minerals, are dissolved in water

On the following model of stream, label zone of sediment production, zone of transportation, zone of deposition. Additionally, list and describe the relative gradient and energy of the streams in each section and what size particles you would expect to find in each section

• zone 1 = zone of sediment production

• gradient: high

• energy: high

• particle size: high (boulders and cobbles)

• zone 2 = zone of transportation

• gradient: moderate

• energy: moderate

• particle size: medium (sand and gravel)

• zone 3 = zone of deposition

• gradient: low

• energy: low

• particle size: fine (silt and clay)

• top is headwaters

• middle is trunk stream

• bottom is mouth

the amount of water that runs off as opposed to infiltrates into the ground depends on?

• intensity and duration of rainfall

• amount of moisture already in soil

• surface material

• slope of land

• extent and type of vegetation

Porosity

• percentage of total volume of rock or sediment that consists of pore spaces

• amount that is stored

Permeability

• the ability to transmit fluids

• how much fluid can be transmitted

Aquifer

• rock or sediment that groundwater moves easily through

• allows water to move

Aquitard

• impermeable bed that hinders or prevents groundwater movement

• does not allow water to move

What is the general shape of the water table? – is it a flat, horizontal line? Why?

• it is the shape of the land surface

• it is not flat

• it rises and falls with topography due to recharge, permeability, and drainage

What characteristics make a good aquifer? Be sure to use permeable and porous in your answer

• a good aquifer is highly porous, meaning it has many spaces to hold water

• and is high permeable, meaning it allows water to flow through it easily

Why and how does a cone of depression form?

• it forms when water is pumped from a well, lowering the water table around its cone-shape

• removing water faster than it can replenish

Compare and contrast springs, hot springs, and geysers.

• springs = natural flow of ground water to surface, typically at normal temperature

• hot springs = groundwater heated by geothermal energy before emerging at surface

• geysers = hot springs that periodically erupt due to pressure buildup in underground chambers

• comparison = all involve groundwater reaching the surface

In what circumstances is ground water a nonrenewable resource?

• OVER PUMPING AND CONTAMINATION

• when it is extracted faster than it can be naturally replenished

• often in arid regions or areas of heavy overuse

If you collect water from a stream in a jar, what part of its load will settle to the bottom, and what portion will remain in the water indefinitely? What part of the stream’s load would probably not be represented in your sample?

• suspended load will settle on the bottom of the jar

• dissolved load will remain in the water indefinitely

• bed load is likely to be missed

You are at the grocery store with a friend looking to buy bottled water. Some brands of bottled water boast that their water is artesian. Other brands promote that their water is from springs. Your friend asks, “Is artesian water or spring water better than other sources?” How would you answer?

Neither is better, both are clean sources, but the choice would be a preference

factors that affect stream or water velocity

• topography or terrain

• friction

• total amount of water

how do you recharge ground water?

rain

trigger

event that causes the slope to become unstable

Angle of repose

the steepest angle at which material remains stable

Liquefaction

during periods of ground shaking, water-saturated surface materials behave as fluid-like masses that flow

Talus Slopes

built by rock falls

Scarp

a slope

How is mass movement different from erosion driven by streams and glaciers? Example?

• involves the downward movement of soil, rock, or debris under the influence of gravity, without the aid of water, wind, or ice. Erosion driven by streams and glaciers involves the transportation of materials by flowing water or moving ice

• Example: A landslide (mass movement) versus sediment transported by a river (erosion)

What are four controls/triggers of mass movement? Be sure to explain how each one works

• GRAVITY AND TRIGGERS CAUSE

• Water: Too much water makes the ground slippery and heavy, causing it to slide downhill (like after heavy rain).

• Steep Slopes: Steep hills are more likely to have materials slide down because gravity pulls stronger on them.

• No Plants: Without plant roots to hold the soil in place, the ground is more likely to move (like when trees are cut down).

• Earthquakes: Shaking from earthquakes can loosen the ground and make it move suddenly.

What are the three ways that material can move during mass movement?

• fal

• slide

• flow

Compare and contrast Debris Flows and Earth Flows

• debris flows – fast, mix of large minerals with water, very destructive

• earth flows – slow, find minerals, gradual movement, less destructive

• both – involve water, loose material downhill movement

List two observations which likely indicate that a slope is failing

• cracks forming on slope surface

• sudden movement or tilt of structures of tilt on slop

Zone of accumulation

• part of a glacier that is characterized by snow accumulation and ice formation

• outer limit of this zone is the snowline

Zone of wastage

part of a glacier beyond the snowline, where annually there is a net loss of ice

Equilibrium line

boundary on a glacier where snow accumulation equals snow melting

Glacial erratic

ice-transported boulder that was not derived from the bedrock near its present site

hydraulic gradient

• slope of the water table

• is determined by finding the height difference between two points on the water table and dividing by the horizontal distance between the two points
  

What is the difference between an ice sheet and a glacier?

ice sheet covers a large area, like antarctica, while a glacier is smaller and typically found in mountains or valleys

What is the glacial budget and how does that affect the glacier?

• balance between accumulation [gains = growth] and ablation [losses = recede]

• accumulation exceeds loss, the glacier grows; if loss exceeds accumulation, the glacier shrinks

How do glaciers erode the landscape?

through plucking, where they pick up rocks, and abrasion, where the ice and carried debris scrape and grind the ground beneath them

What are the three components of the Milankovitch Cycles and what is their net effect?

• eccentricity = variations in shape of earth’s orbit about the sun

• obliquity = changes in the angle of axis

• precession – wobbling of earth’s axis

• net effect – they influence earth’s climate by altering the amount and distribution of solar energy, contributing to long term climate patterns like ice ages

Other than the Milankovitch Cycles, what are two other factors that can affect climate?

• volcanic activity

• solar variability

If Earth were to experience another Ice Age within the next few hundred thousand years, one hemisphere would have substantially more expansive ice sheets than the other, would it be the Northern or Southern Hemisphere? Why?

northern hemisphere because it has more land at higher latitude allows the largerice sheets to form

what are the seasons based on?

tilt of the earth

what are shadow zones?

zones where seismic waves cannot reach