Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and silt. The dominant carbonate mineral in most marls is calcite, but other carbonate minerals such as aragonite, dolomite, and siderite may be present. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay and calcium carbonate, formed under freshwater conditions; specifically an earthy substance containing 35–65% clay and 65–35% carbonate. It also describes a habit of coralline red alga. The term is today often used to describe indurated marine deposits and lacustrine (lake) sediments which more accurately should be named 'marlstone'. Marlstone is an indurated rock of about the same composition as marl, more correctly called an earthy or impure argillaceous limestone. It has a blocky subconchoidal fracture, and is less fissile than shale. The term 'marl' is widely used in English-language geology, while the terms Mergel and Seekreide are used in European references.
Ironstone is a sedimentary rock, either deposited directly as a ferruginous sediment or created by chemical replacement, that contains a substantial proportion of an iron compound from which iron can be smelted commercially. This term is customarily restricted to hard coarsely banded, nonbanded, and noncherty sedimentary rocks of post-Precambrian age. The Precambrian deposits, which have a different origin, are generally known as banded iron formations. The iron minerals comprising ironstones can consist either of oxides, i.e. limonite, hematite, and magnetite; carbonates, i.e. siderite; silicates, i.e. chamosite; or some combination of these minerals.
A geological formation, or formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguish it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region. It is the fundamental unit of lithostratigraphy, the study of strata or rock layers.
The Lincoln Cliff or Lincoln Edge is a portion of a major escarpment that runs north–south through Lindsey and Kesteven in central Lincolnshire and is a prominent landscape feature in a generally flat portion of the county.
In geology, the Bagshot Beds are a series of sands and clays of shallow-water origin, some being fresh-water, some marine. They belong to the upper Eocene formation of the London and Hampshire basins, in England and derive their name from Bagshot Heath in Surrey. They are also well developed in Hampshire, Berkshire and the Isle of Wight. The following divisions are generally accepted:
The Antlers Formation is a stratum which ranges from Arkansas through southern Oklahoma into northeastern Texas. The stratum is 150 m (490 ft) thick consisting of silty to sandy mudstone and fine to coarse grained sandstone that is poorly to moderately sorted. The stratum is cemented with clay and calcium carbonate. In places the sandstone may be conglomeratic or ferruginous.
Granite Mountain is a 7,628-foot (2,325 m) mountain located in Yavapai County, Arizona that covers roughly 12 square miles (31 km2). It was once known as Mount Gurley, for the first governor of the Arizona Territory, John A. Gurley. Its southwest face has a sheer granite cliff approximately 500 feet high that is one of the best locations for rock climbing in the state of Arizona. It is located in the Granite Mountain Wilderness, which is managed as a part of the Prescott National Forest. The mountain stands at the northern end of the Sierra Prietas, and borders Skull Valley on the west, on the northwest by the Santa Maria Mountains, and east by the Williamson Valley.
The Clinton Group is a mapped unit of sedimentary rock found throughout eastern North America. The interval was first defined by the geologist Lardner Vanuxem, who derived the name from the village of Clinton in Oneida County, New York where several well exposed outcrops of these strata can be found. The Clinton Group and its lateral equivalents extend throughout much of the Appalachian Foreland Basin, a major structural and depositional province extending from New York to Alabama. The term has been employed in Kentucky, Maryland, Michigan, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia, though in many of these areas the same interval is referred to as the Rose Hill, Rockwood, or Red Mountain Formations. Historically the term "Clinton" has also been assigned to several lower Silurian stratigraphic units in Ohio and Kentucky which are now known to be significantly older than the Clinton Group as it was originally defined. Many parts of this succession are richly fossiliferous, making the Clinton Group an important record of marine life during the early Silurian. Several economically valuable rock-types are found within this interval, though it is perhaps best known as a significant source of iron ore
The Lias Group or Lias is a lithostratigraphic unit found in a large area of western Europe, including the British Isles, the North Sea, the Low Countries and the north of Germany. It consists of marine limestones, shales, marls and clays.
The Banff Formation is a stratigraphical unit of Devonian age in the Western Canadian Sedimentary Basin.
The Lea Park Formation is a stratigraphical unit of Late Cretaceous age in the Western Canadian Sedimentary Basin, Canada.
The Cypress Hills Formation is a stratigraphic unit of middle Eocene to early Miocene age in the Western Canada Sedimentary Basin. It is named for the Cypress Hills of southeastern Alberta and southwestern Saskatchewan and was first described from outcrops on the slopes of the Cypress Hills in 1930. It is known for preserving a wealth of vertebrate fossils.
Igneous rocks are found in Bukit Timah, Woodlands, and Pulau Ubin island. Granite makes up the bulk of the igneous rock. Gabbro is also found in the area and is found in an area called Little Guilin, named for its resemblance to Guilin in South China. This area is in Bukit Gombak. Sedimentary rocks are found on the western part of Singapore, which is mainly made of sandstone and mudstones. It also includes the southwestern area. Metamorphic rocks are found in the northeastern part of Singapore, and also on Pulau Tekong, off the east coast of Singapore. The rocks are mainly made up of quartzite, and also make up the Sajahat Formation.
The Neoproterozoic Nankoweap Formation, is a thin sequence of distinctive red beds that consist of reddish brown and tan sandstones and subordinate siltstones and mudrocks that unconformably overlie basaltic lava flows of the Cardenas Basalt of the Unkar Group and underlie the sedimentary strata of the Galeros Formation of the Chuar Group. The Nankoweap Formation is slightly more than 100 m in thickness. It is informally subdivided into informal lower and upper members that are separated and enclosed by unconformities. Its lower (ferruginous) member is 0 to 15 m thick. The Grand Canyon Supergroup, of which the Nankoweap Formation is part, unconformably overlies deeply eroded granites, gneisses, pegmatites, and schists that comprise Vishnu Basement Rocks.
Robin's Wood Hill Quarry is a 1.67-hectare (4.1-acre) geological Site of Special Scientific Interest in Gloucestershire, on Robinswood Hill, notified in 1966.
The Albert Formation is a stratigraphic unit of Early Mississippian (Tournaisian) age in the Moncton Subbasin of southeastern New Brunswick. It was deposited in a lacustrine environment and includes fossils of fish and land plants, as well as trace fossils. It also includes significant deposits of oil shale. The oil shale beds are the source rocks for the petroleum and natural gas that has been produced from Albert Formation reservoirs at the Stoney Creek and McCully fields. In addition, the solid asphalt-like hydrocarbon albertite was mined from the Albert Formation at Albert Mines between 1854 and 1884.
The Ferruginous Sands is a geologic formation in England. It preserves fossils dating back to the Aptian Stage of the Cretaceous period. It consists of "a number of heavily bioturbated coarsening-upward units each comprising dark grey sandy muds or muddy sands passing up into fine-to medium-grained grey to green glauconitic sands." The dinosaur Vectaerovenator is known from the formation. Shark teeth are also known from the formation, including those of an indeterminate lamniform shark and Synechodus.
The Carstone Formation is a geologic formation in England. It preserves fossils dating back to the Albian stage of the Cretaceous period. It predominantly consists of "greenish-brown, thick-bedded, cross-bedded, oolitic ferruginous sandstone".
The Worcester Basin or Worcester Graben is a sedimentary basin in central England, filled with mainly Permian and Triassic rocks. It trends roughly north-south and lies between the East Malverns Fault in the west and the Inkberrow Fault in the east. It forms part of a series of Permo-Triassic basins that stretch north-south across England, including the Cheshire Basin and the East Irish Sea Basin. These basins resulted from a regional rifting event that affected parts of North-West Europe, eastern North America and East Greenland.
The Bridport Sand Formation is a formation of Toarcian age found in the Worcester and Wessex Basins of central and southern England. It forms one of the reservoir units in the Wytch Farm oilfield in Dorset. The sandstone is very-fine grained to fine-grained and contains regular narrow bands that are calcite-cemented and more resistant to weathering, giving it a characteristic banded appearance at outcrop, such as in the cliffs between Bridport and Burton Bradstock in Dorset. It is named for Bridport and has previously been known as the Midford Sand(s), Cotteswold Sands, Yeovil Sands and Upper Lias Sand(s). It forms a locally important aquifer, particularly around Yeovil.
