sci Earth Story Flashcards
A principle that states that geologic logic processes that occurred in the past can be explained by current geologic processes.
uniformitarianism
A principle that states that geologic change occurs suddenly.
catastrophism
The scientific study of fossils.
paleontology
The remains or physical evidence of an organism preserved by geological processes.
fossil
A fossilized mark that is formed in soft sediment by the movement of an animal.
trace fossil
A mark or cavity made in a sedimentary surface by a shell or other body.
mold
A type of fossil that forms when sediments fill in the cavity left by a decomposed organism.
cast
A fossil that is found in the rock layers of only one geologic age and that is used to establish the age of the rock layers.
index fossil
The standard method used to divide the Earth’s long natural history into manageable parts.
geologic time scale
The largest division of geologic time.
eon
A unit of geologic time that includes two or more periods.
era
A unit of geologic time into which eras are divided.
period
A subdivision of a geologic period.
epoch
The death of every member of a species.
extinction
