fossil records Flashcards
uniformitarianism
the theory that changes in the earth’s crust during geological history have resulted from the action of continuous and uniform 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 scientific study of life in the geologic past, based on examination of fossilized remains of once living organisms, such as tracks, bones, teeth, plants, and shells.
relative dating
the process of determining if one rock or geologic event is older or younger than another, without knowing their specific ages
absolute dating
measure the physical properties of an object itself and use these measurements to calculate its age.
superposition
a major principle of stratigraphy stating that within a sequence of layers of sedimentary rock
isotope
each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.
radioactive decay
the process in which a radioactive atom spontaneously gives off radiation in the form of energy or particles to reach a more stable state.
half-life
The time required for one-half of the radioactive (parent) isotopes in a sample to decay to radiogenic (daughter) isotopes.
fossil
the preserved remains of plants and animals whose bodies were buried in sediments, such as sand and mud, under ancient seas, lakes and rivers.
trace fossil
a fossil of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself.
mold
a hollow container used to give shape to molten or hot liquid material (such as wax or metal) when it cools and hardens.
cast
mineralized sediment that fills the mold recreates the shape of the remains.
unconformity
a surface of contact between two groups of unconformable strata.
mass extinction
An extinction event is a widespread and rapid decrease in the biodiversity on Earth.
