Geology final

earthquake

vibrations caused by the rupture and sudden movement of rocks along a break or a crack in Earth's crust

What happens during an earthquake?

Before deformation rock layers are not bent

Before an earthquake, rock bends elastically, like a stick that you arch between your hands

Eventually the rock breaks and sliding suddenly occurs on a fault. This break generates vibrations.

displacement

the amount of movement or slip across a fault plane

fault scarp

a small step on the ground surface where one side of a fault has moved vertically with respect to the other

normal faults

form during an extension of the crust. The hanging wall moves down. the Fualt scarp is a slope down-\-

reverse faults

reverse faults for during the shortening of the crust. The hanging wall moves up and the fault is steep -/-

Thrust faults

low angle reverse faults

strike-slip fault

a type of fault where rocks on either side move past each other sideways with little up or down motion

elastic rebound theory

earthquakes happen because stress builds up, causing the rock that is adjacent to the fault to bend elastically until breaking and slipping occurs: the slip relaxes the elastic bending and decreases stress

stick-slip behavior

alternation between stress buildup and earthquake-generating slip events on an existing fault.

Focus (hypocenter)

the point within the earth where an earthquake rupture starts

epicenter

Point on Earth's surface directly above an earthquake's focus

body waves

seismic waves that travel through the Earth's interior

surface waves

seismic waves that travel along the Earth's surface

Compressional Waves (P waves)

waves that cause particles of material to move back and forth parallel to the direction in which the wave itself moves like a slingky

Shear Waves (S waves)

waves that cause particles of material to move back and forth perpendicular to the direction in which the wave itself moves like a rope being moved up and down

L waves (surface waves)

surface waves that cause the ground to shimmy back and forth

R-waves

surface waves that cause the ground to undulate up and down

earthquake intensity

Measure of damage; energy absorbed; changes from location to location used the Modified Mercalli Intensity Scale I-XII

Richter scale

A scale that rates an earthquake's magnitude based on the size of its largest seismic waves.

earthquake magnitude

measure of ground shaking during and earthquake, which depends of distance from epicenter and the geological material.

What four factors effect the severity of the earthquake

1. magnitude of earthquake
2. the distance from the focus
3. the natural substrate at the location
4. the frequency of the waves

how can earthquakes cause damage

shaking of the ground causing infrastructure to collapse

landslides

sediment liquidation

fire

tsunamis

disease

mass movement (mass wasting)

the downslope movement of rock or regolith under the influence of gravity

creep

the slow downhill movement of weathered rock material

Solidfluction

slow (permafrost moves over frozen surface below)

slumping

A type of mass movement involving material moving downhill under its own weight. Spoon shaped

mudflow

Quickly moving downhill flow of soil and rock fragments containing a large amount of water

rock slide

A sudden downslope movement of rock.

downcutting

the process in which water flowing through a channel cuts into the substrate and deepens the channel relative to its surroundings

headwater erosion

lengthening and widening of a stream

drainage network

an array of interconnecting streams that together drain an area

discharge

the total volume of water passing a point along the bank in a second.

capacity

the total quantity of sediment carried by a stream

competence

the maximum particle size a stream can transport

delta

A landform made of sediment that is deposited where a river flows into an ocean or lake

Porosity

the amount of open space in a rock or sediment

permeability

Ability of rock or soil to allow water to flow through it

groundwater drawdown

caused when water is pumped out of well too fast creates a cone of depression too much pumping can also cause a saltwater intrusion

desert

a region that is so arid (dry that it supports vegetation on no more than 15% of its surface, less than 25 cm of rain fall per year on average

subtropical deserts

form do to the global-scale pattern of air circulation where it flows downward in the subtropics warms and absorbs water as it sinks

latitudes of 20-30 degrees

rain-shadow deserts

moist air rises and drops rain on the coastal side of the mountain range. By the time the air has crossed the mountains it is dry.

costal desert

formed along cold ocean currents. rain clouds don't form due to the cold water cooling the air making it dense and not allowing it to rise

continental-interior deserts

desert regions that are dry because they are located so far from the sea that rain might fail to reach them

polar deserts

Cold air at or near the poles can't hold much moisture, so precipitation is low

desert varnish

A dark, rusty-brown coating of iron oxide and magnesium oxide that accumulates on the surface of the rock.

petroglyphs

Rock art carvings made by scratching or pecking the surface of exposed stone.

water erosion in deserts

flash floods can radically alter the landscape in minutes

saltation

the process of rolling or bouncing along the ground wind transports desert sediment as suspended load and surface load

dust storm

haboob

ventifacts

rocks shaped by wind blown sediments

yardangs

ridges that are sculpted and streamlined by wind abrasion and deflation

deflation

the process of lowering the land surface

lag deposit

the coarse sediment left behind in a desert after wind erosion removes the finer sediment

talus

a pile of angular rocks and sediment from a rockfall at the base of cliff

alluvial fan

formed when sediment-laden water flows out onto a plain at the mouth of a canyon, it spreads out over a surface with a gentle slope.

playa

dry, flat, exposed lake bed crust of clay and various salts accumulate on the surface

dunes

mounds of wind-deposited sand

cliff retreat

The change in the position of a cliff face caused by erosion.

mesas, buttes, chimneys

broad, flat-topped erosional remnants bounded on all sides by steep slopes mesas (large) butte (small) chimneys (skinny and tall)

natural arches

a curved formation in rock caused by weathering and erosion through a fin

desert pavement

A mosaic-like stone surface forming the ground in a desert.

cuestas

a ridge with one steep slope and one soft slope

inselbergs

isolated, steep-sided erosional remnants that rise above desert plains

types of sand dunes

barchan (u shaped and goes with the wind), parabolic (u shaped and tails go against the wind), transverse (triangular ridges, perpendicular to wind), longitudinal (longways with the wind), star (middle circle with lines coming out of it)

Desertification

the process by which fertile land becomes desert, typically as a result of drought, deforestation, or inappropriate agriculture.

mountain glaciers (alpine glaciers)

exist in or adjacent to mountainous regions and are make entirely of freshwater.

continental glaciers (ice sheets)

Large, broad, slow-moving glaciers that cover large portions of continental areas.

How do glaciers form?

Glaciers begin to form when snow remains in the same area year-round, where enough snow accumulates to transform into ice. Each year, new layers of snow bury and compress the previous layers. This compression forces the snow to re-crystallize, forming grains similar in size and shape to grains of sugar.

firn

A dense, icy pack of old snow

basal sliding

the movement of a glacier that depends on the pull of gravity and on a thin layer of water between glacier and land

plastic deformation

existing grains slowly change shape without breaking or new grains grow while the old ones disappear. They become flattened and elongates without breaking

crevasse

A deep crack or fissure in the ice of a glacier.

ablation zone

the lower portion of a glacier where there is a net annual loss of ice due to melting and sublimation

glacial striations

Scratches and grooves on bedrock caused by glacial abrasion

ice shelves versus sea ice

continental glaciers that flow into the saw along the coast make ice shelves. Sea ice forms when the ocean surface freezes

Fjords

glacial valleys flooded by seawater

Milankovitch cycles

periodic changes in Earth's rotation and orbit around the sun, could have caused some glacial advances and retreats

what forms oil and gas

organic remains of planktons which settle out and become black organic shale. chemical reactions at elevated temperatures convert the organic matter to kerogen and then to oil

source rock

A rock rich in organic matter which, if heated sufficiently, will generate oil or gas.

reservoir rock

A rock that is sufficiently porous and permeable to store and transmit petroleum.

oil trap

a geologic structure that allows for significant amounts of oil and gas to accumulate

directional drilling

The process of controlling the trajectory of a drill bit to make sure that the drill hole goes exactly where desired.

Hydrofracturing

a well drilled to break open rock to get natural gas, where fluid and other chemicals are injected into rocks containing natural methane gas in order to use the water pressure to fracture the rock and allow the gas to be extracted

coal formation

prehistoric plants buried un-decomposed in oxygen-depleted water of swamps/bogs converted by heat and pressure and compaction changes the debris into peat that wen buried deeply and heated, transforms into coal

strip mining

the removal of strips of soil and rock to expose ore

underground mining

involves the sinking of shafts to reach underground deposits. In this type of mining, networks of tunnels are dug or blasted and humans enter these tunnels in order to manually retrieve the coal.

nuclear power plants

convert the heat produced by nuclear fission of uranium into electrical energy. difficult to dispose of nuclear waste

metal ore

A mineral that contains a compound of the metal and from which the metal is extracted.

magmatic ore deposits

when minerals grow during solidification of melt. In hydrothermal deposits ore minerals precipitate from hot-water solutions

nonmetalic resources

dimension stone, crushed stone, cement (from roasted limestone), evaporites, and clay

what is the layers of hydrocarbons

natural gas, oil, water

volatility

ability to evaporate

fossils

the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.

relative age

The age of a rock compared to the ages of rock layers strata, sedimentary rocks

isotopic (radiometric dating)

uses half-lives to determine the ages of igneous and metamorphic rocks

the Haden Eon (unoffical)

molten, lots of debris from space debris, off gassing, temporary/ unstable atmosphere

Archean Eon (4000-2500 MYA)

the oldest rock form

continental cores form

1st atmosphere

1st sign of life (bacteria and archaea)

Proterozoic Eon (2.5 BYA- 542 MYA)

90% of continental crust formed

photosynthesis adds oxygen to the atmosphere

1st supercontinent Rodinia

Rodinia Supercontinent

during the late Precambrian, a large land mass formed that connected all the major continents of today approximately 1 billion years ago

second part of ohio is attached