Past geological events recorded by "geological clocks" in years.
What is absolute geologic time?
100
The smallest particle that possesses the properties of a particular chemical element.
What is an atom?
100
Rocks that have crystallized from molten rock.
What are igneous rocks?
100
The erosion of rocks largely by wind and water.
What is physical erosion?
100
The mineralogic and/or physical changing of rock caused by high levels of heat and/or pressure - without the melting of the rock.
What is metamorphism?
200
Fractures in Earth's crust along which dislocation occurs.
What is a fault?
200
A naturally formed, solid, chemical substance having a specific composition and a characteristic of crystal structure.
What is a mineral?
200
Molten rock underground.
What is magma?
200
The alteration of rocks by water to produce chemical elements in solution and residual clay.
What is chemical weathering?
200
Metamorphism produced by pressures associated with the development of folded mountain ranges.
What is regional metamorphism?
300
When first accumulating, younger layers of rock overlie older layers of rock.
What is the Principle of Superposition?
300
The study of crystal structures.
What is crystallography?
300
Igneous rocks that form underground.
What are intrusive rocks?
300
Process that contributes to the development of sedimentary rocks.
What is lithification?
300
A coal's heat producing capacity.
What is coal grade?
400
Annual layers of sediment that develop because of seasonal fluctuations in the kind of sediments accumulating on the floor of a body of water.
What is a varve?
400
The external manifestation of an internal crystal structure.
What is crystal form?
400
Rocks that have crystallized from lava upon Earth's surface.
What are volcanic rocks?
400
A rock in which pebble-size grains are angular in shape.
What is breccia?
400
Lineation and foliation.
What are the two types of pressure-induced fabrics?
500
Structures within an organism that no longer serve a useful purpose but appear to be diminutive analogs of functioning structures in other organisms.
What is vestigial organs?
500
When breakage produces a smooth plane.
What is cleavage?
500
The visual coarseness of crystal size.
What is texture?
500
An evaporite mineral that is precipitated within seas and lakes where water has evaporated to a salinity approximately ten times more salty than that of ordinary seawater.