Relative Dating
Absolute Dating
Vocabulary
Fossils
Miscellaneous
100

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

What is superposition?

100

What is the most common method of absolute dating?

What is radiometric dating?

100
a process that involves comparing rock layers with others in a sequence to determine its age
What is relative dating?
100

Fossils are most often preserved in ...

What is rock?

100
a principle that states that geologic processes that occurred in the past can be explained by current geologic processes
What is uniformitarianism?
200

this event occurs when internal forces in the Earth slant rock layers

What is tilting?

200

a radioactive isotope is also called a __________ isotope

What is a parent isotope?

200

the time needed for one-half of a sample of a radioactive substance to undergo radioactive decay

What is half-life?

200

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

What is a trace fossil?

200
a science that contains uniformitarianism and castrophism
What is modern geology?
300

Erosion is one of the major causes of missing rock layers known as...

What are unconformities?

300
the process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element at a steady rate
What is radioactive decay?
300

the scientific study of past life using fossils

What is paleontology?

300
____________ can be used to establish the age of rock layers.
What are index fossils?
300
a mark or cavity made in a sedimentary surface by a shell or other body
What is a mold?
400

an ideal sequence of rock layers that contains all the known fossils and rock formations on Earth, arranged from oldest to youngest

What is a geologic column?

400

a method of determining the age of an object by estimating the relative percentages of a radioactive isotope and a stable isotope

What is radiometric dating?

400

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

What is a cast?

400

Three types of trace fossils...

What are tracks (footprints), burrows, and coprolites?

400

the major time intervals represented by the geologic time scale in order from largest to smallest

What are eons, eras, periods, and epochs?

500

Comparing rock layers to those above or below to figure out the ages.

What relative-age dating.

500

what a a scientist needs to know to figure out the absolute age of a rock (the rate of decay for a ________________ in the rock)

What is the rate of decay (Or length of time the half-lives are)  for a radioactive element in the rock?

500

an atom that has the same number of protons as the other atoms of the same element do but that has a different number of neutrons

What is an isotope?

500

the process in which minerals replace an organism's tissues

What is petrifaction?

500

This unit of geologic time that began 65.5 million years ago and continues to the present...

What is the Cenozoic era?

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