Old Red Sandstone, abbreviated ORS, 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 eastern seaboard of North America. It also extends northwards into Greenland and Svalbard. These areas were a part of the paleocontinent 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. The presence of Old in the name is to distinguish the sequence from the younger New Red Sandstone which also occurs widely throughout Britain.
The Acadian orogeny is a long-lasting mountain building event which began in the Middle Devonian, reaching a climax in the Late Devonian. It was active for approximately 50 million years, beginning roughly around 375 million years ago (Ma), with deformational, plutonic, and metamorphic events extending into the early Mississippian. The Acadian orogeny is the third of the four orogenies that formed the Appalachian Mountains and subsequent basin. The preceding orogenies consisted of the Grenville and Taconic orogenies, which followed a rift/drift stage in the Neoproterozoic. The Acadian orogeny involved the collision of a series of Avalonian continental fragments with the Laurasian continent. Geographically, the Acadian orogeny extended from the Canadian Maritime provinces migrating in a southwesterly direction toward Alabama. However, the northern Appalachian region, from New England northeastward into Gaspé region of Canada, was the most greatly affected region by the collision.
The Taconic orogeny was a mountain building period that ended 440 million years ago (Ma) and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the east coast of the United States. As the mountain chain eroded in the Silurian and Devonian periods, sediment spread throughout the present-day Appalachians and midcontinental North America.
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.
The Caledonian orogeny was a mountain-building cycle recorded in the northern parts of the British Isles, the Scandinavian Caledonides, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occurred from the Ordovician to Early Devonian, roughly 490–390 million years ago (Ma). It was caused by the closure of the Iapetus Ocean when the Laurentia and Baltica continents and the Avalonia microcontinent collided.
The Dalradian Supergroup is a stratigraphic unit in the lithostratigraphy of the Grampian Highlands of Scotland and in the north and west of Ireland. The diverse assemblage of rocks which constitute the supergroup extend across Scotland from Islay in the west to Fraserburgh in the east and are confined by the Great Glen Fault to the northwest and the Highland Boundary Fault to the southeast. Much of Shetland east of the Walls Boundary Fault is also formed from Dalradian rocks. Dalradian rocks extend across the north of Ireland from County Antrim in the north east to Clifden on the Atlantic coast, although obscured by later Palaeogene lavas and tuffs or Carboniferous rocks in large sections.
The geology of Scotland is unusually varied for a country of its size, with a large number of different geological features. There are three main geographical sub-divisions: the Highlands and Islands is a diverse area which lies to the north and west of the Highland Boundary Fault; the Central Lowlands is a rift valley mainly comprising Palaeozoic formations; and the Southern Uplands, which lie south of the Southern Uplands Fault, are largely composed of Silurian deposits.
The Central Lowlands, sometimes called the Midland Valley or Central Valley, is a geologically defined area of relatively low-lying land in southern Scotland. It consists of a rift valley between the Highland Boundary Fault to the north and the Southern Uplands Fault to the south. The Central Lowlands are one of the three main geographical sub-divisions of Scotland, the other two being the Highlands and Islands which lie to the north, northwest and the Southern Uplands, which lie south of the associated second fault line. It is the most populated of Scotland’s three geographical regions.
The Grampian Group is an estimated 9,000 m thick sequence of metamorphosed Neoproterozoic sedimentary rocks that outcrop across the Central Highlands of Scotland, east of the Great Glen. It forms a part of the Dalradian Supergroup. The sequence thickness at any one place is limited to 5km.
The Badenoch Group is a sequence of metamorphosed Tonian age sedimentary rocks that outcrop across the Central Highlands of Scotland, east of the Great Glen. This rock sequence has formerly been referred to as the Central Highland Migmatite Complex and the Central Highland Division.
The geology of Maine is part of the broader geology of New England and eastern North America.
This article describes the geology of the Cairngorms National Park, an area in the Highlands of Scotland designated as a national park in 2003 and extended in 2010. The Cairngorms National Park extends across a much wider area than the Cairngorms massif itself and hence displays rather more varied geology.
The geology of Sudan formed primarily in the Precambrian, as igneous and metamorphic crystalline basement rock. Ancient terranes and inliers were intruded with granites, granitoids, and volcanic rocks. Units of all types were deformed, reactivated, intruded, and metamorphosed during the Proterozoic Pan-African orogeny. Dramatic sheet flow erosion prevented almost any sedimentary rocks from forming during the Paleozoic and Mesozoic. From the Mesozoic into the Cenozoic, the formation of the Red Sea depression and complex faulting led to massive sediment deposition in some locations and regional volcanism. Sudan has petroleum, chromite, salt, gold, limestone, and other natural resources.
The geology of national parks in Britain strongly influences the landscape character of each of the fifteen such areas which have been designated. There are ten national parks in England, three in Wales and two in Scotland. Ten of these were established in England and Wales in the 1950s under the provisions of the National Parks and Access to the Countryside Act 1949. With one exception, all of these first ten, together with the two Scottish parks were centred on upland or coastal areas formed from Palaeozoic rocks. The exception is the North York Moors National Park which is formed from sedimentary rocks of Jurassic age.
The geology of Loch Lomond and The Trossachs National Park in the southwestern part of the Scottish Highlands consists largely of Neoproterozoic and Palaeozoic bedrock faulted and folded and subjected to low grade metamorphism during the Caledonian orogeny. These older rocks, assigned to the Dalradian Supergroup, lie to the northwest of the northeast – southwest aligned Highland Boundary Fault which defines the southern edge of the Highlands. A part of this mountainous park extends south of this major geological divide into an area characterised by younger Devonian rocks which are assigned to the Old Red Sandstone.
The Grampian orogeny was an orogeny that affected Scotland in the middle of the Ordovician. At the time, Scotland was part of proto-North American continent Laurentia.
The Loch Ness Supergroup is one of the subdivisions of the Neoproterozoic sequence of sedimentary rocks in the Scottish Highlands. It is found everywhere in tectonic contact above the older Wester Ross Supergroup. It is thought to be unconformably overlain by the Cryogenian to Cambrian Dalradian Supergroup.
The Highland Border Complex is an assemblage of rocks of probable early Cambrian to late Ordovician age, found as fault-bounded blocks of variable lithology exposed immediately to the southeast of the Highland Boundary Fault at the edge of the Grampian Highlands, Scotland.
The Sgurr Beag Thrust is an important tectonic structure within the Neoproterozoic metasedimentary rock sequences of the Scottish Highlands. The thrust, or similar structures correlated with it, form the boundary between rocks of the Glennfinnan Group and the underlying Morar Group. It divides the Wester Ross Supergroup from the Loch Ness Supergroup. The history of this structure remains poorly understood although it is thought to be at least partly of Caledonian age.
The Highland Border Ophiolite (HBO) is a set of rocks that are ophiolitic in character found within the Highland Border Complex. They are exposed in a series of fault-bounded outcrops along the line of the Highland Boundary Fault that forms the southeastern boundary to the Grampian Highlands in Scotland. They represent fragments of a piece of oceanic crust or exhumed mantle that has been obducted onto continental crust. These rocks provide an important constraint on models of how the current geometry arose during the Caledonian Orogeny.
