Geo Exam 3 (for mid term)

.What happens to a rock during metamorphosis: Density increases

pressure causes a rearrangement of atoms

What happens to a rock during metamorphosis: Mineral orientations change

collapse of intercrystalline structures

What happens to a rock during metamorphosis: minerals are mobilized

pressure causes mobilization

Metamorphic facies

a group or association of rocks that indicate where they were formed

Index mineral

a way to determine the degree of metamorphism a rock has experienced

Proliths

the orgininal rock that has undergone metamorphism// usually sedimentary

Why are metamorphic rocks not used for things such as counter tops or home utilities?

metaphormic rocks are weak in one plane

Largest mine in the world

Beigum mines, Utah

How do you make cement

Limestone

Metamorphic rocks are used to aggregate ____

pool tables, roofs, gravel

How many deaths has their been due to earthquakes in the last 2,000 years?

3.5 million

Example of a earthquake that spawned tsunamis

Indian Ocean tsunami and a tsunami on the Eastern coast of Japan

Most earthquakes are caused by sudden motion along____

newly formed crustal fault or existing fault

Earthquakes are also caused by____

magma movement, volcanic eruptions, landslides, meteorites impacts, and nuclear detonations

What are seismic gaps?

places that haven’t “slipped” recently. They can be particulary dangerous

Short-term predictions

earthquakes that may happen on a scale of weeks or months

Earthquake

A sudden movement on a fault

Fault

a plane or surface of the Earth in which breaks are going to occur

Normal fault

Hanging wall goes down relative to footwall due to crustal stretching

Strike-slip

no vertical motion, one block slides sideways (latterally) past the other

Better infrastructure equals…..

lower death rates

Earthquakes mainly occur ____

on the boarders of tectonic plates

What type of earthquake was the CA, Charleston quake of 1886?

Continental transform fault

What type of quake was the New Madrid quake of 1812?

Active rift

What type of earthquake was the AK (Arkansas) earthquake of 1964?

Collision zone

What percent of earthquakes are not near modern plate boundaries and where do they actually occur?

5%, places of crustal weakness related to failed rifts or former shear zones

What happened in New Madrid, Missouri in 1811-1912?

three magnitude 7.0 earthquakes struck

typical pattern of seismic activity surrounding a major earthquake

foreshocks —> earthquake —→ afterschocks

foreshock

occurs as stress builds up along a fault line, causing smaller tremors before the release of significant energy

aftershcoks

numerous smaller earthquakes occuring as the Earth’s crust adjusts to the changes caused by the main earthquake

P-waves: Solids

cause particles to move back and forth in the same direction as the wave’s propagation, can travel through quickly and efficently, moves side to side

P-waves: Liquids

loses their ability to transmit shear stress, causing particles to move only in the direction of the wave’s propagation (speed of wave), travels or slowly, moves side to side

Shear waves (s-waves)

moves vertically (up and down)

Rayliegh waves

travels along the surface of the earth, rolling motion, slower than S and P

Love waves

horizontal motion perpendicular (intersecting horizontally) to the direction of wave propagation, slower than P and S waves, faster than Rayleigh

Seismograph

Measure up and down, and side to side

Richter Scale ML

uses magnitude quantify the size or strength of an earthquake

1883 Charleston Quake

Using the MII scale, there are 10s 9s 8s from rift valleys

Ground motion depend on the____

substrate

surface-waves scale Ms

bases on P-wave measurements on deeper quakes

Moment magnitude scale (Mw)

the best measure. based on characteristics of different seismic waves and the area and displacement of fault slip

Magnitude

a measurement of size based on the maximum amplitude of seismograph waves

Earthquake proofing

using cross framing for smaller buildings, anchoring buildings in bedrock with flexible cable, rollers and spring

Soil liquefaction

subsurface liquifies and removes layers of clay or mud// usually close to a body of water

Secondary Effects: Fires

as shaking occurs, gas lines buried within the sidewalks blow up

Secondary Effects: Tsunami

mound of water generates from a fault in the ocean, gravity pulls down the mound of water, creating a Tsunami

Boxing Day Tsunami

275,000 deaths, 100ft of water

Suma-Andaman earthquake 12/26/04

shallow quake, lasted 10 mins, caused deaths 8,00km away, generated 100ft waves

Tsunami Bouy

senses pressures increases from changes in sea thickness

Evidence of previous earthquakes

sand volcanoes, fault scarp, trees curving, stable wood fragment

What percent of the US population lives at the coast

50%

Passive margin

wide continental shelf

Active continental coast

narrow continental shelf, volcanoes

Hydrologic cycle

the changes in sea level are affected by temperature

Where could a huge volume of water possibly come from

ice on land or glaciers

Ocean water movement: Northern hemisphere

Clockwise currents

Ocean water movement: Southern hemisphere

counter-clock wise

Gulf stream:

brings warm water from the gulf into the ocean

Coriolis

the deflection of the wind from its oirginal direction of travel because of its distance from the Earth

WHat is the circumfrence of the equator

24,000 miles

What happens when salinity goes up

water becomes more dense

What happens when water gets warmer

it gets less dense

what percent of streams makes up earth’s total volume

0.0002%

How large is the watershed of the Mississippi

1.25 million square miles

What percent of salinity makes up all oceans

3.5%

what percent of salinity makes up the Dead Sea

26%-35%

What percent of salinity makes up the Great Salt Lake

15%-25%

What are waves directly generated by

wind

Average ocean depth

13,00ft

Fjords

deep water ways along the coast

Drowned river valleys (passive)

a river valley that is full of ocean water, result of glacial melt

Mississippi delta

swampy delta, coastal plane

Why are Sanddunes important?

they maintain beach structure

Movement of sand

comes from the ocean and goes onto the beach

foreshore

the part of a shore or coastline that lies between the water at low tide and the land or cliffs. underwater 2x a day and exposed 2x a day

Beach face

boundary between foreshore and backshore

wave length measures from

crest to crest

wave amplitude measures from

trough to crest

swash

movement of water on the beach

backwash

movement of water off of the beach

As waves collapse…

it expands its energy on top of the beach, loosing mass

latorial drift

the drift of the sand in the dominant direction of the breaksers

Where do sands come from?

weathering and erosion in north georgia mountains

What is happening to the North end of Jekyll (driftwood beach?)

sand is eroding away due to interuption of littoral drift

grions

prevents movements of sand

breakwaters

interrupts transport of sand

West coast beaches

steep topography, no barrier islands, exposed igneous structures, gravel beaches// black basalt, primary input of sediment come from cliff erosion

Pocket beaches

small beaches isolated by two headlines. not finely grained rock, made up of igneous components

What is happening to Tybee island

it a barrier island that is is coming towards the west due to sea level rise

when sea level falls it causes….

deltas

when sea level falls it causes….

flooding and headlands

Drowned valley example

Chesapeake bay and Delaware bay

What percent of our surface is covered by oceans?

75%

What determines the shape of our coastlines?

wave energy

What divides GA from SC?

savannah

What river flows through Milledgeville?

oconnee

what divides GA and FL

St. mary’s

Where does the Columbia river cut through?

The Cascade Range

San Francisco is on what ype of boundary

transform

New Madrid is on what type of boundary

intraplate