Fossil Record Vocabulary

Question 1

uniformitarianism

Answer 1

A principle that states that geologic processes that occurred in the past can be explained by current geologic processes

Question 2

catastrophism

Answer 2

A principle that states that geologic change occurs suddenly

Question 3

paleontology

Answer 3

The scientific study of fossils

Question 4

relative dating

Answer 4

Any method of determining whether an event or object is older or younger that other events or objects

Question 5

absolute dating

Answer 5

A principle that states that younger rocks lie above older rocks if the layers have not been disturbed

Question 6

superposition

Answer 6

An arrangement of rock layers in which the oldest rocks are at the bottom

Question 7

isotope

Answer 7

An atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons ( and thus a different atomic mass)

Question 8

radioactive decay

Answer 8

The process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element

Question 9

half-life

Answer 9

The time needed for half of a sample of a radioactive substance to undergo radioactive decay

Question 10

fossil

Answer 10

The remains or physical evidence of an organism preserved by geological processes

Question 11

trace fossil

Answer 11

A fossilized mark that is formed in soft sediment by the movement of an animal

Question 12

mold

Answer 12

A mark or cavity made in a sedimentary surface by a shell or other body

Question 13

cast

Answer 13

A type of fossil that forms when sediments fill in the cavity left by a decomposed organism

Question 14

unconformity

Answer 14

A break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time

Question 15

mass extinction

Answer 15

The extinction of many species an once

Question 16

Jurassic period

Answer 16

A geologic period and system that spanned 56 million years from the end of the Triassic period to the beginning of the Cretaceous period

Question 17

Cretaceous period

Answer 17

The period between 145.5 and 65.5 million years ago spanning from the last period of the Mesozoic Era, following the Jurassic and ending with the extinction of the dinosaurs

Question 18

Devonian period

Answer 18

A geologic period and system spanning 60 million years from the end of the Silurian period to the beginning of the Carboniferous period

Question 19

Quaternary period

Answer 19

The current and most recent of the three periods of the Cenozoic Era

Question 20

Permian period

Answer 20

A geologic period and system which spans 47 million years from the end of the Carboniferous period to the beginning of the Triassic period