geologic history

Question 1

geologic history

Answer 1

study and interpretation of earth’s past

Question 2

relative age

Answer 2

the age of rocks or events compared to the age of other rocks or events

(ex. i am a teenager)

Question 3

absolute age

Answer 3

the age of a rock, object, or event in years

(ex. i am 14 years old)

Question 4

how do scientists determine the relative ages of rock layers

Answer 4

• uniformitarianism
• principle of original horizontality
• principle of superposition

Question 5

uniformitarianism

Answer 5

the geologic processes that took place in the past are generally similar to those that take place now

Question 6

principle of original horizontality

Answer 6

sediments are deposited in horizontal layers that are parallel to the surface they were deposited on

Question 7

what do tilted or folded layers indicate

Answer 7

the crust has been deformed

Question 8

principle of superposition

Answer 8

in undisturbed layers, the oldest layer is on the bottom, and each overlaying layer is younger

• does not apply if layers have been overturned or faults have forced over rock over younger rock

Question 9

igneous intrusions and extrusions

Answer 9

as hot magma squeezes into cracks and zones of weakness, the cooling magma pastes its heat energy to the nearby rock

Question 10

how to tell if this intrusion is younger or older

Answer 10

if its younger there will be burn marks

Question 11

unconformity

Answer 11

a gap in the rock record caused by the burial of an eroded surface by younger sediments. shown by a wavy line

Question 12

how do unconformities happen

Answer 12

1. submergence
2. deposition of sediments
3. emergence
4. erosion
5. submergence
6. deposition

Question 13

where does the rock need to be eroded

Answer 13

above water

Question 14

where does the rock need to be to be created from deposition

Answer 14

underwater

Question 15

folding

Answer 15

layers of sedimentary rock that have been bent or warped by crustal forces

Question 16

tilting

Answer 16

formally horizontal rock layers that have been tilted at an angle by crustal activity

Question 17

faulting

Answer 17

a crack of weakness in earth’s crust along which movement occurs during an earthquake

Question 18

law of cross cutting

Answer 18

a disruption that cuts through rock or another geologic feature must be younger than the rock or the other geologic feature

Question 19

when is there contact metamorphism

Answer 19

when the intrusion is younger

Question 20

how do you know when there is contact metamorphism

Answer 20

there would be dashed lines

Question 21

how to know when rock layers are deposited before the fault

Answer 21

when the fault line goes through it

Question 22

what do you know about the geologic cross-sections when the bottom layer is sedimentary

Answer 22

submergence is the first thing that happened

Question 23

erosional surface

Answer 23

a surface where rock has been worn away by wind, water, or ice, often creating an unconformity

Question 24

subsidence

Answer 24

the sinking or downward movement of the earth’s surface

Question 25

uplift

Answer 25

the rising of earth’s surface due to tectonic forces

Question 26

emergence

Answer 26

when land rises above sea level, often due to uplift or falling sea levels

Question 27

submergence

Answer 27

when land sinks below sea level, often due to subsidence or rising sea levels