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The Ochil Fault is the geological feature which defines the southern edge of the Ochil Hills escarpment in Scotland.
North of the fault, Devonian lava flows and pyroclastic deposits slope gently down, thinning towards the north. These are in part overlain by Old Red Sandstone rocks formed later in the Devonian period. Because the deposits thin towards the north, and there are few signs of volcanic necks within the Ochil Hills themselves, it is thought that the eruptive centres were south of the fault, however these are buried deep beneath the Carboniferous rocks including coal measures which are found beneath the low-lying carse lands to the south. [1]
To put this in perspective, the prominent hill Dumyat which defines the western extremity of the Ochil Hills has a height of 418 metres (1,371 ft). The nearest colliery, Manor Powis, approximately 2 kilometres (1.2 mi) south of the fault, was approximately the same depth, in carse land that is scarcely above sea level, and was mining coal from Carboniferous strata at least many hundreds of metres above the top of the Devonian deposits. The Ochil Fault was active from the earliest part of the Carboniferous period, allowing the marine swamps in which the coal-producing vegetation flourished to be periodically overlain by layers of sand, forming sandstone, or silt, forming shale, in a number of cyclic subsidences. These occurred in the form of basins, and the pattern of movements was complex, however it is known that the greatest vertical movement was centred about 1 kilometre (0.62 mi) east of the town of Alva, and almost certainly exceeded 5 kilometres (3.1 mi) vertically. The deepest deposits of coal measures are obviously found in this region, but this has not been mined to its full extent, probably due to the great depth involved.
The point of maximum downwards movement south of the fault lies just south of the Silver Glen, which happens to be the part of the Ochil Hills where the greatest extent of mineralisation has been discovered. The minerals, including ores of silver and cobalt, were probably emplaced by hydrothermal solutions percolating upwards through various minor faults and fractures, in the Tertiary period.
The Ochil Fault remained active throughout geological time, and some later movements allowed intrusive eruptions of diorite or quartz-dolerite to rise at various places along its length.
Modern movements of the fault are very minor but occasionally give rise to discernible earthquakes, [2] particularly in the village of Menstrie, and the town of Tillicoultry. However the latter may be easily confused with the collapse of old room and pillar coal mine workings which undoubtedly underlie the southern part of the town.
The Ochil Fault is one of Britain's finest examples of a fault line scarp, [3] and can be best appreciated from vantage points such as the Wallace Monument near Stirling. [4]
The Llano Uplift is a geologically ancient, low geologic dome that is about 90 miles (140 km) in diameter and located mostly in Llano, Mason, San Saba, Gillespie, and Blanco counties, Texas. It consists of an island-like exposure of Precambrian igneous and metamorphic rocks surrounded by outcrops of Paleozoic and Cretaceous sedimentary strata. At their widest, the exposed Precambrian rocks extend about 65 miles (105 km) westward from the valley of the Colorado River and beneath a broad, gentle topographic basin drained by the Llano River. The subdued topographic basin is underlain by Precambrian rocks and bordered by a discontinuous rim of flat-topped hills. These hills are the dissected edge of the Edwards Plateau, which consist of overlying Cretaceous sedimentary strata. Within this basin and along its margin are down-faulted blocks and erosional remnants of Paleozoic strata which form prominent hills.
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.
In Scottish geography, a Carse is an area of fertile, low-lying land occupying certain Scottish river valleys, such as that of the River Forth.
The geology of India is diverse. Different regions of the Indian subcontinent contain rocks belonging to different geologic periods, dating as far back as the Eoarchean Era. Some of the rocks are very deformed and altered. Other deposits include recently deposited alluvium that has yet to undergo diagenesis. Mineral deposits of great variety are found in the subcontinent in huge quantities. Even India's fossil record is impressive in which stromatolites, invertebrates, vertebrates and plant fossils are included. India's geographical land area can be classified into the Deccan Traps, Gondwana and Vindhyan.
The geology of the county of Shropshire, England is very diverse with a large number of periods being represented at outcrop. The bedrock consists principally of sedimentary rocks of Palaeozoic and Mesozoic age, surrounding restricted areas of Precambrian metasedimentary and metavolcanic rocks. The county hosts in its Quaternary deposits and landforms, a significant record of recent glaciation. The exploitation of the Coal Measures and other Carboniferous age strata in the Ironbridge area made it one of the birthplaces of the Industrial Revolution. There is also a large amount of mineral wealth in the county, including lead and baryte. Quarrying is still active, with limestone for cement manufacture and concrete aggregate, sandstone, greywacke and dolerite for road aggregate, and sand and gravel for aggregate and drainage filters. Groundwater is an equally important economic resource.
The Highland Boundary Fault is a major fault zone that traverses Scotland from Arran and Helensburgh on the west coast to Stonehaven in the east. It separates two different geological terranes which give rise to two distinct physiographic terrains: the Highlands and the Lowlands, and in most places it is recognisable as a change in topography. Where rivers cross the fault, they often pass through gorges, and the associated waterfalls can be a barrier to salmon migration.
The Stirling Sill is an outcropping of a large quartz-dolerite intrusion or sill that underlies a large part of central Scotland, and may be contiguous at great depth. The sill is of very late Carboniferous age or more probably Permian, as it penetrates the coal measures, often in bedding planes between the various strata. In places, it rises through fractures in the strata to a new level, forming features that, at the surface, would be called dikes.
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 Lomond Hills, also known outside the locality as the Paps of Fife, are a range of hills in central Scotland. They lie in western central Fife and Perth and Kinross, Scotland. At 522 metres (1,713 ft) West Lomond is the highest point in the county of Fife.
The Geology of Yorkshire in northern England shows a very close relationship between the major topographical areas and the geological period in which their rocks were formed. The rocks of the Pennine chain of hills in the west are of Carboniferous origin whilst those of the central vale are Permo-Triassic. The North York Moors in the north-east of the county are Jurassic in age while the Yorkshire Wolds to the south east are Cretaceous chalk uplands. The plain of Holderness and the Humberhead levels both owe their present form to the Quaternary ice ages. The strata become gradually younger from west to east.
The geology of the Orkney islands in northern Scotland is dominated by the Devonian Old Red Sandstone (ORS). In the southwestern part of Mainland, this sequence can be seen to rest unconformably on a Moinian type metamorphic basement.
The geology of Monmouthshire in southeast Wales largely consists of a thick series of sedimentary rocks of different types originating in the Silurian, Devonian, Carboniferous, Triassic and Jurassic periods.
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 geology of Georgia is the study of rocks, minerals, water, landforms and geologic history in Georgia. The country is dominated by the Caucasus Mountains at the junction of the Eurasian Plate and the Afro-Arabian Plate, and rock units from the Mesozoic and Cenozoic are particularly prevalent. For much of its geologic history, until the uplift of the Caucasus, Georgia was submerged by marine transgression events. Geologic research for 150 years by Georgian and Russian geologists has shed significant light on the region and since the 1970s has been augmented with the understanding of plate tectonics.
The geology of Uzbekistan consists of two microcontinents and the remnants of oceanic crust, which fused together into a tectonically complex but resource rich land mass during the Paleozoic, before becoming draped in thick, primarily marine sedimentary units.
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 geology of the Gower Peninsula in South Wales is central to the area's character and to its appeal to visitors. The peninsula is formed almost entirely from a faulted and folded sequence of Carboniferous rocks though both the earlier Old Red Sandstone and later New Red Sandstone are also present. Gower lay on the southern margin of the last ice sheet and has been a focus of interest for researchers and students in that respect too. Cave development and the use of some for early human occupation is a further significant aspect of the peninsula's scientific and cultural interest.
The geology of Staffordshire in the West Midlands region of England is largely characterised by sedimentary bedrock of late Palaeozoic to early Mesozoic age overlain by a suite of superficial materials deposited during the Quaternary period. The extraction of coal, limestone and clay have been significant industries within the county.