Geology terminology

thumb|Afro-Eurasia, the largest landmass on Earth

There are several conflicting usages of geosphere, variously defined.

unit in chronostratigraphy

geological term for a type of fracture in rock

Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time.

sequence of rock depositions defining a chronostratigraphic unit corresponding to a specific epoch on the geologic time scale

A chronozone or chron is a unit in chronostratigraphy, defined by events such as geomagnetic reversals (magnetozones), or based on the presence of specific fossils (biozone or biochronozone). According to the International Commission on Stratigraphy, the term "chronozone" refers to the rocks formed during a particular time period, while "chron" refers to that time period.

In stratigraphy, paleontology, geology, and geobiology, an erathem is the total stratigraphic unit deposited during a certain corresponding span of time during an era in the geologic timescale.

idealized composite unit of the geologic record representing the totality of rock strata laid down during a certain period of the geologic time scale

thumb|200px|right|Horseshoe Canyon Formations exposed in Horseshoe Canyon (Alberta)|Horseshoe Canyon near [[Drumheller, Alberta.]] thumb|200px|right|Oxfordian (Upper Jurassic) cyclic sediments at Péry-Reuchenette, near Tavannes, kanton Bern, Switzerland. Alternating layers are limestone (light, more competent) and [[marl/clay; dominant cycle is the 200000 year-cycle.]]

volume of rock defined by its petrographic, lithologic or paleontologic features

A relict is a surviving remnant of a natural phenomenon.

list of definitions of geological terms

thumb|This vug in the Cascade Range is partially filled with [[quartz crystals.]]

Wikimedia glossary list article

In natural science, subaerial (literally "under the air") has been used since 1833, notably in geology and botany, to describe features and events occurring or formed on or near the Earth's land surface. They are thus exposed to Earth's atmosphere. This may be contrasted with subaqueous events or features located below a water surface, submarine events or features located below a sea surface, subterranean events or features located below ground, or subglacial events or features located below glacial ice such as ice sheets.

In materials science, friability ( ), the condition of being friable, describes the tendency of a solid substance to break into smaller pieces under stress or contact, especially by rubbing. The opposite of friable is indurate.