Geology Exam 2

Front 1

Conglomerate

Back 1

rock formed from lithification from rounded clasts

Front 2

size

Back 2

flowing water and other weathering elements change the size

Front 3

sorting

Back 3

index of environments ability to separate grain size

Front 4

rounding

Back 4

the longer the travel distance, the rounder it is

Front 5

lithification

Back 5

process of turning sediments into rock

Front 6

depositional environments

Back 6

condition in which sediments were deposited

Front 7

examples of depositional environment

Back 7

glacial, beach and river environments

Front 8

mudcracks

Back 8

when wet mud dries out from sun filled with sediments. says what sediments formed, got wet and dried out

Front 9

beach environment

Back 9

lots of cross bed sands, similar grain size, high energy in the surf sun where the waves break. similar look as streams

Front 10

mountain-stream environment

Back 10

stream runs down mountain carrying large clasts. during floods, large clasts settle forming gravel and boulder beds while the stream carries finer sediments and mud

Front 11

glacial environment

Back 11

ice moves sediments of any size. when glaciers move downhill it carries along all the sediments. when the ice melts away, it drops its load of sediments making a pile of glacial till

Front 12

Limestones

Back 12

inorganic - water turns cloudy, white

organic- forms from crusty algae, armors themselves stiff can stand like branchy plants, dies and tissues released away

Front 13

Micrite

Back 13

inorganic and organic

Front 14

bioclastic limestone

Back 14

shell ragments from storms

Front 15

reef rock

Back 15

coral reef

Front 16

absolute time

Back 16

4.6 BY

Front 17

relative time

Back 17

places events in a sequence relative to each other.

Front 18

index fossils

Back 18

working with a single species that is useful. robust hard parts, made of something stable like silica or calcium phosphate, abundant, geographic range thats useful. you also dont want that species to have be around for a long time

Front 19

overlapping range of fossils

Back 19

helps narrow the time that fossil was around

Front 20

radiometric dating

Back 20

defining the age of a rock by measuring the rate of decay of radioactive elements in the rock.

Front 21

Alpha particles

Back 21

2 protons, 2 neutrons

Front 22

beta particles

Back 22

1 neutron in nucleus

Front 23

Half life

Back 23

all atoms like a time bomb and no one knows when they will go off.

Front 24

Random date of decay

Back 24

Can come up of average rate of decay that leads to calculation of half life. time for half of a given mass to decay from parent to stable daughter

Front 25

Uranium

Back 25

2 isotopes

Front 26

What makes a useful grain crystal to use?

Back 26

need something to incorperate radioisotopes, never has any of the daughter, only parent, chemically stable so daughter is preserved

Front 27

Geologic time scale

Back 27

breaking history into slugs of time that has boundaries based on fossils and sediment rocks

cannot date sedimentary rocks from this because the inherit crystal radioisotopes from older rocks

Front 28

What are the unconformities?

Back 28

Disconformity - sed ontop of sed , same orientation

Angular conformity - sed ontop of sed, rocks folded or tilted by faulting before being uplifted and eroded

nonconformity - young sed on top of older bedrock, sedimentary rocks overlie intrusive rocks. rocks under cooled and were uplifted and eroded

Front 29

1920, and 30s

Back 29

continental drift fitted continents across atlantic, simlar geological rock sequence, similar types of metamorphic and igneous rocks

Front 30

how pangae was explained

Back 30

large land animals same across continents, glacial ice sheets were present in warm climates that could not produce that such as Africa

Front 31

Gonguana sequence

Back 31

deposits of thick cross-beds, dessert dune deposits, going through climate changes, including mostly sediments like basalt. This was a sign if Pangaea breaking up

Front 32

when were sea maps released

Back 32

in the 50s by eason and tharp, creating a delailed map of the sea floor, mid ocean ridges that we use today

Front 33

polar wandering

Back 33

explained magnetic fields

Front 34

declamation

Back 34

compass, poles

Front 35

inclamation

Back 35

angle between earths magnetic field and horizontal, shows latitude. determined this as magnetic poles wandering across earth. all continents had different polar wanderings showing that they were moving

Front 36

polarity normal

Back 36

north and south pole

Front 37

reverse polarity

Back 37

north pole is south pole, vise versa

if new basalt was forming at mid ocean ridges, you get a point were reverse polarity is present

Front 38

if oceanic crust is forming, how do people compensate for that?

Back 38

earthquakes began at oceanic crust, right at the trench edge. they were shallow, 100km. Behind the volcanoes it got as deep as 700 km where no earthquakes can occur.

Front 39

Types of stresses

Back 39

pressure- feel same stress from all sides

tention - rock pulled apart

compression - rock squeezed

sheer stress - one side moves sideways past the other

Front 40

strain

Back 40

change in shape and size

Front 41

elastic

Back 41

change in shape of a rock when stress goes away

Front 42

Plastic

Back 42

permanent

Front 43

brittle

Back 43

breaks easy

Front 44

what are the tubular features, faults and orientations

Back 44

strike - long end of a sediments

Dip - angle of its horizontal

Front 45

physical principles

Back 45

superposition - sequence of sedimentary rock layers, each layer younger than the next

original horizontality - slide downslope before lithification making it deposited horizontally

original continuity - generated in continuous sheets,

cross-cutting relations - one geological feature crosses another

inclusion - contains fragment of other rocks, the fragment is older than the intrusion