Ardvreck Group | |
---|---|
Stratigraphic range: Lower Cambrian | |
Type | Group |
Sub-units | Eriboll Formation, An-t-Sron Formation |
Underlies | Durness Group |
Overlies | Lewisian complex or Torridon Group |
Thickness | up to 142 m |
Lithology | |
Primary | quartzite, quartz arenite |
Location | |
Region | Hebridean Terrane |
Country | Scotland |
Extent | Northwest Highlands |
Type section | |
Named for | Ardvreck Castle |
The Ardvreck Group is a stratigraphic group of early Cambrian age found in the Northwest Highlands of Scotland. It lies unconformably on gneisses of the Lewisian complex or sandstones of the Torridon Group. It consists of two formations, the basal quartzites and quartz arenites of the Eriboll Formation and the overlying dolomitic siltstones and sandstones and quartz arenites of the An-t-Sron Formation. It is overlain conformably by the Ghrudaidh Formation of the Durness Group. The Ardvreck Group was at one time known as the "Eriboll Group". [1]
Sandstone is a clastic sedimentary rock composed mainly of sand-sized silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Quartzite is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of hematite. Other colors, such as yellow, green, blue and orange, are due to other minerals.
The Moine Thrust Belt or Moine Thrust Zone is a linear tectonic feature in the Scottish Highlands which runs from Loch Eriboll on the north coast 190 kilometres (120 mi) south-west to the Sleat peninsula on the Isle of Skye. The thrust belt consists of a series of thrust faults that branch off the Moine Thrust itself. Topographically, the belt marks a change from rugged, terraced mountains with steep sides sculptured from weathered igneous, sedimentary and metamorphic rocks in the west to an extensive landscape of rolling hills over a metamorphic rock base to the east. Mountains within the belt display complexly folded and faulted layers and the width of the main part of the zone varies up to 10 kilometres (6.2 mi), although it is significantly wider on Skye.
A quartz arenite or quartzarenite is a sandstone composed of greater than 90% detrital quartz. Quartz arenites are the most mature sedimentary rocks possible, and are often referred to as ultra- or super-mature, and are usually cemented by silica. They often exhibit both textural and compositional maturity. The two primary sedimentary depositional environments that produce quartz arenites are beaches/upper shoreface and aeolian processes.
Cranstackie is a mountain of 801 metres (2,628 ft) in Sutherland, the northwestern tip of the Scottish Highlands. It is a Corbett located west of Loch Eriboll and northeast of Foinaven. Like its lesser Corbett neighbour Beinn Spionnaidh to the northeast, its summit ridge is covered with massive blockfields and blockpiles of Cambrian sandstone, in fact quartz-arenite which is less sharp and loose than the pure white quartzite found further south. The two hills present a steep escarpment to the west, from where the usual way ascends through an easy gap, with a dip slope to the east. Below the summit ridges, Lewisian gneiss basement supports grassy and mossy slopes offering better going. On the first OS maps, the hill was named Crann Stachach, suggested to mean peaky or uneven hill of the tree but 'crann' is more likely a horizontal 'beam' here; the tor-stippled skyline is notable from the main road to the west. The name was anglicised on subsequent maps and stated to be of obscure meaning, supposedly Norse - 'stac' is indeed a sharp hillock.
The Clarens Formation is a geological formation found in several localities in Lesotho and in the Free State, KwaZulu-Natal, and Eastern Cape provinces in South Africa. It is the uppermost of the three formations found in the Stormberg Group of the greater Karoo Supergroup rocks and represents the final phase of preserved sedimentation of the Karoo Basin.
The Ordovician Kittatinny Formation or Kittatinny Limestone is a dolomitic limestone formation in New Jersey. The Kittatinny Limestones are located primarily in the Kittatinny Valley where it lies above the Ordovician Martinsburg Formation within the long valley running from Picatinny Arsenal in Rockaway Township, southwest toward Chester Township. It overlies the Cambrian Hardyston Quartzite.
The Aztec Sandstone is an Early Jurassic geological formation of primarily eolian sand from which fossil pterosaur tracks have been recovered. The formation is exposed in the Mojave Desert of Arizona, California and Nevada. Aztec Sandstone is named after the Aztec Tank, a lake in the Spring Mountain region of Nevada.
A QFL diagram or QFL triangle is a type of ternary diagram that shows compositional data from sandstones and modern sands, point counted using the Gazzi-Dickinson method. The abbreviations used are as follows:
Lithic sandstones, or lithic arenites, or litharenites, are sandstones with a significant (>5%) component of lithic fragments, though quartz and feldspar are usually present as well, along with some clayey matrix. Lithic sandstones can have a speckled or gray color, and are usually associated with one specific type of lithic fragment.
The Hebridean Terrane is one of the terranes that form part of the Caledonian orogenic belt in northwest Scotland. Its boundary with the neighbouring Northern Highland Terrane is formed by the Moine Thrust Belt. The basement is formed by Archaean and Paleoproterozoic gneisses of the Lewisian complex, unconformably overlain by the Neoproterozoic Torridonian sediments, which in turn are unconformably overlain by a sequence of Cambro–Ordovician sediments. It formed part of the Laurentian foreland during the Caledonian continental collision.
The Clarence Moreton Basin is a Mesozoic sedimentary basin on the easternmost part of the Australian continent. It is located in the far north east of the state of New South Wales around Lismore and Grafton and in the south east corner of Queensland. It is the part of the Great Artesian Basin that extends to the east coast in Australia's central eastern lowlands.
The Potsdam Sandstone, more formally known as the Potsdam Group, is a geologic unit of mid-to-late Cambrian age found in Northern New York and northern Vermont and Quebec and Ontario. A well-cemented sandstone of nearly pure quartz, in the 19th century it was widely used in construction and in refractory linings for iron furnaces.
The geology of the Isle of Skye in Scotland is highly varied and the island's landscape reflects changes in the underlying nature of the rocks. A wide range of rock types are exposed on the island, sedimentary, metamorphic and igneous, ranging in age from the Archaean through to the Quaternary.
The Dox Formation, also known as the Dox Sandstone, is a Mesoproterozoic rock formation that outcrops in the eastern Grand Canyon, Coconino County, Arizona. The Dox Formation comprises the bulk of the Unkar Group, the older subdivision of the Grand Canyon Supergroup. The Unkar Group is about 1,600 to 2,200 m thick and composed of, in ascending order, the Bass Formation, Hakatai Shale, Shinumo Quartzite, Dox Formation, and Cardenas Basalt. The Unkar Group is overlain in ascending order by the Nankoweap Formation, about 113 to 150 m thick; the Chuar Group, about 1,900 m (6,200 ft) thick; and the Sixtymile Formation, about 60 m (200 ft) thick. The entire Grand Canyon Supergroup overlies deeply eroded granites, gneisses, pegmatites, and schists that comprise Vishnu Basement Rocks.
The Bokkeveld Group is the second of the three main subdivisions of the Cape Supergroup in South Africa. It overlies the Table Mountain Group and underlies the Witteberg Group. The Bokkeveld Group rocks are considered to range between Lower Devonian (Lochkovian) to Middle Devonian (Givetian) in age.
The Durness Group is a geological group, a carbonate-dominated stratigraphic unit that forms a c. 170 km long narrow and discontinuous outcrop belt along the north-western coast of Scotland from the Isle of Skye and Loch Kishorn in the south to Durness and Loch Eriboll in the north. It forms the youngest part of the foreland basin of the Moine Thrust Belt in the Scottish Northwest Highlands and is incorporated into this belt's lowermost thrust sheets, where it is often affected by thrust faulting. It overlies the Ardvreck Group.
The geology of Sweden is the regional study of rocks, minerals, tectonics, natural resources and groundwater in the country. The oldest rocks in Sweden date to more than 2.5 billion years ago in the Precambrian. Complex orogeny mountain building events and other tectonic occurrences built up extensive metamorphic crystalline basement rock that often contains valuable metal deposits throughout much of the country. Metamorphism continued into the Paleozoic after the Snowball Earth glaciation as the continent Baltica collided with an island arc and then the continent Laurentia. Sedimentary rocks are most common in southern Sweden with thick sequences from the last 250 million years underlying Malmö and older marine sedimentary rocks forming the surface of Gotland.
The Santa Teresa Formation is a geological formation of the western Eastern Ranges of the Colombian Andes, west of the Bituima Fault, and the southern Middle Magdalena Valley. The formation spreads across the western part of Cundinamarca and the northern portion of Tolima. The formation consists of grey claystones intercalated by orange quartz siltstones and sandstones of small to conglomeratic grain size. The thickness at its type section has been measured to be 118 metres (387 ft) and a maximum thickness of 150 metres (490 ft) suggested.
The Coronado Sandstone is a geologic formation that is exposed in eastern Arizona and western New Mexico. It is Cambrian in age based on its position in the stratigraphic column.