flashcards
Uniformitarianism
a principle that states that geologic processes that occured in the past can be explained by curred geologic processes
Catastrophism
the theory that changes in the earth’s crust during geological history have resulted chiefly from sudden violent and unusual events
Paleontology
the branch of science concerned with fossil animals and plants.
Relative dating
Any method of determinging whether an event or object is older or younger than other events or object
Absolute dating
is the process of determining an age on a specified chronology in archaeology and geology.
Superposition
a principle that states that younger rocks lie above older rocks if the layers have not been disturbed
Isotope
an atom that has the same number of protons
Radioactive decay
also known as nuclear decay, radioactivity or nuclear radiation
half-life
the time taken for the radioactivity of a specified isotope to fall to half its original value
Fossil
the remains or physical evidence of an organism preserved by geoloical processes
trace fossil
A fossilized mark that is formed in soft sediment by the movment of an animal
Mold
a mark or cavity made in a sedimentary surface
cast
a type of fossil that forms when sediments
unconformity
a break in the geologic record created when rock layers
mass extinction
of a large number of species within a relatively short period of geological time
Jurassic period
between the Triassic and Cretaceous periods, lasting for 55 million years during which dinosaurs and ammonites flourished.
Cretaceous period
as the period between 145.5 and 65.5 million years ago,
Devonian period
is a geologic period and system of the Paleozoic,
Quaternary period
is the name for the time in which we live. It spans the two most recent geologic epochs
Permian period
lasted from 299 to 251 million years ago* and was the last period of the Paleozoic Era.
