rock and fossil record

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

Answer 4

any method of determining whether an event or object is older or younger than other events or objects.

Question 5

superposition

Answer 5

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

Question 6

unconformity

Answer 6

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 7

absolute dating

Answer 7

any method of measuring the age of an event or object in years.

Question 8

isotope

Answer 8

Isotopes are two or more types of atoms that have the same atomic number and position in the periodic table, and that differ in nucleon numbers due to different numbers of neutrons in their nuclei.

Question 9

radioactive decay

Answer 9

when an unstable atomic nucleus loses energy by radiation.

Question 10

half life

Answer 10

the amount of time it takes for one-half of the radioactive isotope to decay.

Question 11

fossil

Answer 11

the preserved remains, or traces of remains, of ancient organisms.

Question 12

trace fossil

Answer 12

a fossilized mark that formed iin soft sediment by the moment of an animal

Question 13

mold

Answer 13

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