Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostratigraphy, biostratigraphy, and chronostratigraphy.
The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also extends northwards into Greenland and Svalbard. These areas were a part of the ancient continent of Euramerica/Laurussia. In Britain it is a lithostratigraphic unit to which stratigraphers accord supergroup status and which is of considerable importance to early paleontology. For convenience the short version of the term, ORS is often used in literature on the subject. The term was coined to distinguish the sequence from the younger New Red Sandstone which also occurs widely throughout Britain.
The Los Angeles Basin is a sedimentary basin located in Southern California, in a region known as the Peninsular Ranges. The basin is also connected to an anomalous group of east-west trending chains of mountains collectively known as the Transverse Ranges. The present basin is a coastal lowland area, whose floor is marked by elongate low ridges and groups of hills that is located on the edge of the Pacific Plate. The Los Angeles Basin, along with the Santa Barbara Channel, the Ventura Basin, the San Fernando Valley, and the San Gabriel Basin, lies within the greater southern California region.
The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone, and limestone and is light gray, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.
Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology.
A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks, with the oldest rocks on the bottom and the youngest on top.
The Animikie Group is a geologic group composed of sedimentary and metasedimentary rock, having been originally deposited between 2,500 and 1,800 million years ago during the Paleoproterozoic era, within the Animikie Basin. This group of formations is geographically divided into the Gunflint Range, the Mesabi and Vermilion ranges, and the Cuyuna Range. On the map, the Animikie Group is the dark gray northeast-trending belt which ranges from south-central Minnesota, U.S., up to Thunder Bay, Ontario, Canada. The Gunflint Iron Range is the linear black formation labeled G, the Mesabi Iron Range is the jagged black linear formation labeled F, and Cuyuna Iron Range is the two black spots labeled E. The gabbro of the Duluth Complex, intruded during the formation of the Midcontinent Rift, separates the Mesabi and Gunflint iron ranges; it is shown by the speckled area wrapping around the western end of Lake Superior.
The Cid Formation is a metavolcanic rock and mudstone geologic formation in North Carolina. It consists of a lower unnamed mudstone member with intermittent volcanic flows and the Flat Swamp Member, which is characterized by pyroclastic flows. It preserves fossils dating back to the Ediacaran period.
The Sonyea Group is a geologic group in the northern part of the Appalachian Basin. It preserves fossils dating back to the Devonian period.
The Cashaqua Shale is a geologic formation in New York. It preserves fossils dating back to the Devonian period.
The Rock Stream Formation is a geologic formation in New York. It preserves fossils dating back to the Devonian period.
The Unalaska Formation is a Miocene Era geologic formation on Amaknak Island and Unalaska Island, in the Aleutian Islands archipelago of southwestern Alaska.
The Beattie Peaks Formation is a geologic formation of Early Cretaceous (Valanginian) age in the Western Canada Sedimentary Basin that consists primarily of marine mudstone. It is present in the northern foothills of the Canadian Rockies and the adjacent plains in northeastern British Columbia.
The Beaver Mines Formation is a stratigraphic unit of Early Cretaceous (Albian) age in the Western Canada Sedimentary Basin that is present in southwestern Alberta and southeastern British Columbia, Canada. It was established by G.B. Mellon in 1967 who named it for the hamlet of Beaver Mines, Alberta. It contains a variety of plant fossils.
The Dent Group is a group of Upper Ordovician sedimentary and volcanic rocks in north-west England. It is the lowermost part of the Windermere Supergroup, which was deposited in the foreland basin formed during the collision between Laurentia and Avalonia. It lies unconformably on the Borrowdale Volcanic Group. This unit was previously known as the Coniston Limestone Group or Coniston Limestone Formation and should not be confused with the significantly younger Coniston Group.
The geology of Northumberland in northeast England includes a mix of sedimentary, intrusive and extrusive igneous rocks from the Palaeozoic and Cenozoic eras. Devonian age volcanic rocks and a granite pluton form the Cheviot massif. The geology of the rest of the county is characterised largely by a thick sequence of sedimentary rocks of Carboniferous age. These are intruded by both Permian and Palaeogene dykes and sills and the whole is overlain by unconsolidated sediments from the last ice age and the post-glacial period. The Whin Sill makes a significant impact on Northumberland's character and the former working of the Northumberland Coalfield significantly influenced the development of the county's economy. The county's geology contributes to a series of significant landscape features around which the Northumberland National Park was designated.
The Huntersville Chert or Huntersville Formation is a Devonian geologic formation in the Appalachian region of the United States. It is primarily composed of mottled white, yellow, and dark grey chert, and is separated from the underlying Oriskany Sandstone by an unconformity. The Huntersville Chert is laterally equivalent to the Needmore Shale, which lies north of the New River. It is also laterally equivalent to a sandy limestone unit which is often equated with the Onondaga Limestone. These formations are placed in the Onesquethaw Stage of Appalachian chronostratigraphy, roughly equivalent to the Emsian and Eifelian stages of the broader Devonian system.
The geology of Montana includes thick sequences of Paleozoic, Mesozoic and Cenozoic sedimentary rocks overlying ancient Archean and Proterozoic crystalline basement rock. Eastern Montana has considerable oil and gas resources, while the uplifted Rocky Mountains in the west, which resulted from the Laramide orogeny and other tectonic events have locations with metal ore.
The geology of South Korea includes rocks dating to the Archean and two large massifs of metamorphic rock as the crystalline basement, overlain by thick sedimentary sequences, younger metamorphic rocks and volcanic deposits. Although extent is small, Geology is diverse, and There are diverse rocks which is formed during long-time from Precambrian to Cenozoic Era in Korea Peninsula.
This article describes the geology of Dartmoor National Park in Devon, in south-west England. Dartmoor gained national park status in 1951 but the designated area of 954 km2 (368 sq mi) extends beyond the upland of Dartmoor itself to include much of the surrounding land, particularly in the northeast. The geology of the national park consists of a 625 km2 (241 sq mi) core of granite intruded during the early Permian period into a sequence of sedimentary rocks originating in the Devonian and Carboniferous periods. These rocks were faulted and folded, sometimes, intensely, during the Variscan orogeny. Thermal metamorphism has also taken place around the margins of the granite pluton altering the character of the sedimentary rocks whilst mineral veins were emplaced within the granite. A small outlier of Palaeogene sediments occurs on the eastern boundary of the national park.
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