Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.



H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

20 Cards in this Set

  • Front
  • Back
A principle that states that geologic change occurs suddenly.
The science that deals with the study of past life (fossils).
Scientists who study past life using fossil data.
relative dating
sedimentary rock
A rock that forms from compressed or cemented layers of sediment.
A principle that states that younger rocks lie above older rocks if the layers have not been disturbed.
A break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time.
law of crosscutting relationships
The principle that a fault or body of rock is younger than any other body of rock that it cuts through.
absolute dating
Any method of measuring the age of an event or object in years.
radioactive decay
The process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element.
radiometric dating
A mass of igneous rock that forms when magma is injected into rock and then cools and solidifies.
What are isotopes of an element?
Isotopes of an element have nuclei with the same number of protons (the same atomic number) but different numbers of neutrons. Therefore, isotopes have different mass numbers, which give the total number of nucleons-the number of protons plus neutrons
Where are most fossils preserved?
Most fossils are preserved in sedimentary rock.
Where do you find the oldest fossils?
In the oldest layers of rock.
What happens after every half-life?
Half of the parent material will have decayed and become daughter material.
Why is the fossil record not complete?
The fossil record is incomplete because we don't have a record of every organism that ever lived; animals with soft parts don't fossilize; weathering destroys fossils.
How do you figure out the absolute age of rock?
If you know the half-life of a sample, and can measure the ratio of parent and daughter isotopes, you can find the absolute age of the rock.