Chapter 5 Vocabulary Flashcards
Uniformitarianism
A principle that geologic processes that occurred in the past can be explained by current geologic processes.
Catastrophism
A principle that states that geologic change occurs suddenly.
Relative Age
The approximate age of fossils or other objects in rock layers determined by comparing whether the surrounding rock layers are younger or older.
Relative Dating
Any method of determining whether an event or object is older or younger than other events or objects.
Geologic Column
An ordered arrangement of rock layers that is based on the relative ages of the rocks and in which the oldest rocks are at the bottom.
Absolute Dating
Any method of measuring the age of an event or object in years.
Paleontology
The scientific study of fossils.
Fossil
The trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock.
Trace Fossil
A fossilized mark that formed in sedimentary rock by the movement of an animal on or within soft sediment.
Mold
A mark or cavity made in a sedimentary surface by a shell or other body
Cast
A type of fossil that forms when sediments fill in the cavity left by a decomposed organism.
Index Fossil
A fossil that is used to establish the age of a rock layer because the fossil is distinct, abundant, and widespread and the species that formed that fossil existed for only a short span of geologic time.
Geologic Time Scale
The standard method used to divide Earth’s long natural history into manageable parts.
Eon
The largest division of geologic time; divided into eras.
Era
A unit of geologic time that includes two or more periods
