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
the three types of unconformities
What are disconformities, nonconformities, and angular unconformities?
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 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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