Mineral deposits and rock masses designated with reference to their origin; as, the siliceous formation about geysers; alluvial formations; marine formations.
A group of beds of the same age or period; as, the Eocene formation.
An identifiable single geologic horizon.
In geology, a "formation" is the most common kind of local rock. Formations have uniform chemical make-ups, texture, and structure, and so can be distinguished from neighboring rock. Germinate: to sprout or start to grow
Fundamental body of rock which is characterized by similarities such as rock type, chemical composition and structures, textures or fossils distinct from adjacent rock bodies. The sediments of Fossil Lake are found within the Green River Formation.
a set of rocks that are or once were horizontal, share some distinctive features, and are large enough to be mapped.
A geological term that describes a succession of strata similar enough to form a distinctive geological unit useful for mapping or description.
is a reference to a group of rocks of the same age extending over a substantial area of a basin.
A geological term applied to an underground rock stratum; in the gas industry, usually the one from which gas or oil is produced.
a sequence of rocks usually from the same epoch.
A rock unit, being a subdivision of a group or subgroup.
Mappable unit of rock, given a formal name that typically refers to a place with a type section of the formation.
A laterally continuous rock unit with a distinctive set of characteristics that make it possible to recognize and map from one outcrop or well to another. The basic rock unit of stratigraphy.
A formation is a set of rock layers that consists dominantly of a certain rock type or combination of types.
a unit or rock with well defined upper and lower boundaries that is unique and mappable.
The basic rock unit distinctive enough to be readily recognizable in the field and widespread and thick enough to be plotted on a map. It describes the strata, such as limestone, sandstone, shale, or combinations of these and other rock types. Formations have formal names, such as shale, or combinations of these and other rock types formations have formal names, such as Joliet Formation or St. Louis Limestone (Formation), generally derived from the geographic localities where the unit was first recognized and described.
In geology, the fundamental unit in rock stratigraphic classification, consisting of a distinctive mappable body of rock.
larger vegetation units, such as forest, forest-step (prairie), arctic or alpine dwarf scrub etc. The term goes back to Grisebach (1839), a pioneer in the science of plant geography.
(geology) the geological features of the earth
a collection of separate units, each with their own command structures
a group of rocks having a similar composition
a rock unit that has a distinctive appearance--in other words, a geologist can tell it apart from the rock layers around it
a rock unit that is distinctive enough in appearance that a geologic mapper can tell it apart from the surrounding rock layers
a set of rock layers that share an age range and one or more distinctive physical characteristics, can be followed for some distance as a group, and can be drawn on an outcrop map
A body of rock identified by unique physical characteristics and relative position.
A particular body of rock or sequence of rock strata. It is identified by its composition and texture and its position relative to other rock units. Formal formation names consist of two parts: the name of a locality and either the word formation or the name of a type of rock (e.g., sandstone, shale).
a formation is a regionally extensive mappable geologic unit with reasonably constant lithology; an aquifer may comprise one or more formations or may consist of particular high-conductivity beds within a formation.
The term for the primary unit in stratigraphy consisting of a succession of strata useful for mapping or description which possesses certain distinctive lithologic and other features, i.e. the Mississauga Formation.
basic stratigraphic term defined as a distinct mappable rock unit.
A layer of rock having characteristics that is distinct and recognizable. The rock layer is thus mappable, even among other layers of similar rocks. The thickness can range from a few feet to hundreds of feet. Distinctive features might include mineral composition; texture, diagnostic plant or animal remains (fossils) contained in the formation, etc.
Layer of rock with distinct characteristics, such as color, particle size and composition that can be identified and mapped over extended distances.
the term used in the local classification of rocks to define a geological unit that can be mapped. Formations are classified according to the physical features of the rock. Formation names usually include the geographical location where the rock was originally described together with the nature of the dominant rock type, e.g., Durness Limestone.
a group of rock layers that are recognizable from one place to another
A sedimentary bed or series of beds sufficiently alike or distinctive to form an identifiable geologic unit.
A strata of rocks named after its geographical location and dominant rock type or combination of rock types.
A term commonly used for a speleothem. More correctly, a distinct layer of rock from one geologic period, such as the Edwards Limestone in Texas.
A separate layer of rock or group of intermingled beds.
The basic geologic unit of lithostratigraphic (rock-strata) classification. A formation must be identifiable on the basis of easily recognized physical properties and widespread enough to be mapped at a regional scale. A formation can be divided into smaller units (called members) where these, too, are recognizable and mappable. Formations may be combined into groups when useful and appropriate.
A body or layer of rock with distinct upper and lower boundaries, consisting of a single type of rock or of closely related types; the basic unit of stratigraphy. They may be grouped together in larger assemblages called groups, series, and systems.
A rock formation is a body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it.
The two basic types of geologic formations are defined below: Consolidated A homogeneous layer composed of solid rock or cemented earthen material. Unconsolidated A formation composed of loose, unsorted earthen materials, or particles such as clay, silt, sand, gravel, or stones.
A grouping of sedimentary rocks that are the same age and of the same appearance. They are usually named after a type locality and/or the dominant rock type present, e.g. the Blacksmith Dolomite, named after Blacksmith Canyon, south of Logan. Examples of rock formations in Cache Valley area. Examples of rock formations in Ogden area.
Formation - A body of rock identified by lithologic characteristics or stratigraphic position; it is mappable at the surface and traceable through the subsurface.
A distinctive body of rock that is given a name and separated from other rocks on a geological map (see Group).
A (named) succession of sedimentary beds having some common characteristic.
a unit of geological mapping, consisting of a large and persistent stratum of rock
Sedimentary bed or deposit composed substantially of the same minerals throughout and distinctive enough to be a unit.
The primary unit of stratigraphy. A formation must be mapable and possess distinguishing characteristics.
A rock deposit or structure of homogeneous origin and appearance.
a unit of rock that may be mapped over a large area.
A group of similar consolidated (that is, relatively solid) rocks or unconsolidated (that is, relatively loose) minerals.
Used to describe a particular sequence of rocks of similar character recognisable over distance. Also an oil industry term used to describe a particular layer being tested for oil and gas.
The ordinary unit of geologic mapping recognized by field criteria consisting of a larger, persistent, and mappable strata of predominantly one kind of rock or sediment type.
a bed or deposit composed throughout of substantially the same kind of rock; often a lithologic unit. Each formation is given a name, frequently as a result of the study of the formation outcrop at the surface and sometimes based on fossils found in the formation.
Any assemblage of rocks which have some character in common, whether of origin, age, or composition. Often, the word is loosely used to indicate anything that has been formed or brought into its present shape.
a rock unit possessing distinctive characteristics, such as mineral content, fossils, or color, that allows it to be distinguished from adjacent rock units.
An identifiable layer of rocks named after its geographical location and dominant rock type.
stratigraphic unit comprising several members
Used in well-logging literature in a general sense to refer to all material penetrated by a drill hole without regard to its lithology or structure; used in a stratigraphic sense, formation refers to a named body of rock strata with unifying lithologic features.
A body of rock identified by physical characteristics and stratigraphic position and mappable at the earth's surface or traceable in the subsurface. The formation is the fundamental unit in lithostratigraphic classification. Formations can be subdivided into members or lumped together into groups.
A group of similar consolidation (that is, relatively solid) rocks of unconsolidated (that is, relatively loose) minerals.
In lithostratigraphy, the fundamental and mappable unit based upon the lithology of the rocks included within it. See Briggs and Crowther (1990), p. 462.
A distinctive, mappable rock unit representing deposition under a uniform set of conditions and during a limited period of time.
A formation is a group of beds used in stratigraphy. This is the smallest unit on a geological map. Formations are grouped together into a group. See also Member.
A body of rock both large enough to be mapped and distinct from surrounding rock. Usually takes its name from a geographic feature in the area where it is exposed on the surface (the Saganaga Batholith, for example).