Geo test 2

Can you predict an earthquake

No, the factors that cause an earthquake changes, build up of stress and how much energy is stored, fault surface and friction changes

what are the different types of strain on a rock

compression- squeeze and shorten

tension- stretch a body and pull it apart

shearing - push two sides in opposite direction

That theory explains whey earthquakes happen?

elastic rebound theory - the build up of stress leads to elastic deformation. when the strength of the rock is exceeded the rock ruptures with slip along faults and releases elastic energy

What is an earthquake

an event of ground shaking caused by slip along a fault within the earth, causes a release of energy

what is the focus of a earthquake

point of first fault rapture, at depth of crust

what is the epicenter of an earthquake

point on land surface directly above focus

Where do most earthquakes occur

At plate boundries, always occur in the lithosphere

what is lateral shortening and where does it take place

when the crust is shorten by compression, occurs at continent- continet convergent boundaries

What strike slip faults

faults that happen at a transform boundry, left lateral and right lateral - act like little guy and see which direction slab moved

why do thrust faults happen

to shorten and thicken mountain belts

What is a thrust fault

a special kind of reverse fault- has a smaller angle caued by a lot of pressure

What is a reverse fault

fault caused by compression in conversion zones, rock moves up

what is a normal fault

fault caued by ententsion, happens in rifting centers, hanging wall slips down

where is the footwall

block below the fault

where is the hanging wall

block above the fault

What are synclines

folds that are downward

what are anticlines

folds that are upwards

what are the two styles of deformation and what are their characteristics

brittle - cold, fast and lower presure but high stress

ductile - high temp, high pressure, slow rate

What can deformation result in

folding, rotation, dislacement

When did the Cenozoic era start

65 million years ago

What happened in the cenozoic era

age of mimmals, uplift of worlds mountain ranges, cooling and formation fo polar ice sheets

What era did primates apear and when

cenozoic around 20 milion years ago

When did the genus homo appear

2.6 million years ago

When was the Hadeon Eon and what happened

4.54-4 billion years, earliest earth

What is the Archean Eon and what happened

4-2.6 million years ago, earliest evidence for life stromatolites in Australia (3.2 billion years old)

how did the earliest life evolved

under pretty extreme conditions - hypothermophiles

how is molecules on earth composed

left handed amino acids and right handed sugars

When was the proterozoic eon and what happened

Appearence of oxygen, where life became multicellular , 2,500 - 600 million years ago

How old is the first proof for complex life

2.1 billion years , first unamiguous fossile evidence for eukaryotes

When was the evidence for oxygen

2.4-2.1 billion years ago in the proterozoic eon, called banded iorn formations (BIFs)

When was the earliest animals

640-650 million years ago, proterozoic, no hard parts- bones or shells

When was the phanerozoic eon and what happened

last 541 million years, visible life, when hard parts appeared

What happened in the early paleozoic

life deversified with shells

When did the cambrian explosion happen

the phanerozoic eon

What was it called with land was invaded

ordovician (485-443 million years) first vertebrates and primitvie land plants

When did the first land amimlas develop

360 milllion years ago, tiktaalik- lobe finned fish

what happened in the late mesozoic

high sea levels and shallow continental seasons - there was the western interor seaway, ocean anoxic event

When was the cretaceous - paleogene (K-Pg) boundry event

66 million years - impact on earth blocked the sun and cooled the earth causing extinction of warm adapted animals

What was left in the soil after K-pg boundary

iridium anomally

What are index minerals

andalusite- low temp low pressure

kyanite - low temp, and high pressure

sillimanite - high tempature and pressure

What is thermal metamorphism

heating by plutonic intrusion

what is burial metamorphism

deep burial in a basin

what is dynamic metamrphism

shearing in a fault zone

what is regional metamorphism

pressure and tempature changes due to orogenesis

what is hydrotermal metamorphism

alteration by hot water leaching

what is subduction metamorphism

high pressure and low temp alteration

what is shock metamorphism

extreme high pressure from a bolide impact

which direction does foliation form

pressure caues new sheet siliate minerals to form perpendicular to the dircetion of stress

what happens with neocrystallization

new rock crystals form - clay and quarts → quartz, garrnet, mica

what happens with recrystalization

large new crystals form

what happens with pressure solution

chemical process of dissolution and reprecipitation, grains ends are sawed off- now none circular

what happens with plastic deformation

existing grains flatten by deforming internally , shape change without breaking

what tempature does metamorphism occor

250 -850 degrees C

how are inorganic chemical sedimentary rocks formed

precipiates- form as solubility of dissolved ions in solution chages

evaporation- leaves ions after water is removed

what are biochemical sed rocks made of

shells of marine animals - calcite and silica

what is aphanitic texture

small crystals

what is phaneritic texture

large crystals

what is porphyritic texture

large and big crystals