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46-627: The Blackmore Vale ( / ˈ b l æ k m ɔːr / ; less commonly spelt Blackmoor ) is a vale , or wide valley , in north Dorset , and to a lesser extent south Somerset and southwest Wiltshire in southern England . The vale is part of the Stour valley and part of the natural region known as the Blackmoor Vale and Vale of Wardour . The southern periphery of the vale is in the Dorset National Landscape area. To

92-427: A detachment layer is present. Thrust tectonics is associated with the shortening and thickening of the crust, or the lithosphere. This type of tectonics is found at zones of continental collision , at restraining bends in strike-slip faults, and at the oceanward part of passive margin sequences where a detachment layer is present. Strike-slip tectonics is associated with the relative lateral movement of parts of

138-414: A broader floodplain may result. Deposition dominates over erosion. A typical river basin or drainage basin will incorporate each of these different types of valleys. Some sections of a stream or river valleys may have vertically incised their course to such an extent that the valley they occupy is best described as a gorge , ravine , or canyon . Rapid down-cutting may result from localized uplift of

184-533: A cirque glacier. During glacial periods, for example, the Pleistocene ice ages, it is in these locations that glaciers initially form and then, as the ice age proceeds, extend downhill through valleys that have previously been shaped by water rather than ice. Abrasion by rock material embedded within the moving glacial ice causes the widening and deepening of the valley to produce the characteristic U or trough shape with relatively steep, even vertical sides and

230-432: A framework for understanding the earthquake and volcanic belts that directly affect much of the global population. Tectonic studies are important as guides for economic geologists searching for fossil fuels and ore deposits of metallic and nonmetallic resources. An understanding of tectonic principles can help geomorphologists to explain erosion patterns and other Earth-surface features. Extensional tectonics

276-594: A narrow valley with steep sides. Gill is used to describe a ravine containing a mountain stream in Cumbria and the Pennines . The term combe (also encountered as coombe ) is widespread in southern England and describes a short valley set into a hillside. Other terms for small valleys such as hope, dean, slade, slack and bottom are commonly encountered in place-names in various parts of England but are no longer in general use as synonyms for valley . The term vale

322-432: A relatively flat bottom. Interlocking spurs associated with the development of river valleys are preferentially eroded to produce truncated spurs , typical of glaciated mountain landscapes. The upper end of the trough below the ice-contributing cirques may be a trough-end . Valley steps (or 'rock steps') can result from differing erosion rates due to both the nature of the bedrock (hardness and jointing for example) and

368-465: A slower rate than that of the main valley floor; thus the difference in the two valleys' depth increases over time. The tributary valley, composed of more resistant rock, then hangs over the main valley. Trough-shaped valleys also form in regions of heavy topographic denudation . By contrast with glacial U-shaped valleys, there is less downward and sideways erosion. The severe downslope denudation results in gently sloping valley sides; their transition to

414-541: A town sandwiched between the Dorset Downs and Cranborne Chase. When viewed from above (e.g. from the chalk escarpments) the vale appears quite uniform - a large expanse of green, lush, low-lying land - but in geological terms it comprises alternating belts of different clay and limestone soils (and greensand at the foot of the chalk), which give rise to subtle variations in topography and appearance, and which affect land use. The majority of human settlements are built on

460-427: A valley between its sides is referred to as the valley floor. The valley floor is typically formed by river sediments and may have fluvial terraces . The development of a river valley is affected by the character of the bedrock over which the river or stream flows, the elevational difference between its top and bottom, and indeed the climate. Typically the flow will increase downstream and the gradient will decrease. In

506-510: A variety of transitional forms between V-, U- and plain valleys can form. The floor or bottom of these valleys can be broad or narrow, but all valleys have a shoulder. The broader a mountain valley, the lower its shoulders are located in most cases. An important exception is canyons where the shoulder almost is near the top of the valley's slope. In the Alps – e.g. the Tyrolean Inn valley –

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552-670: A watercourse only rarely. In areas of limestone bedrock , dry valleys may also result from drainage now taking place underground rather than at the surface. Rift valleys arise principally from earth movements , rather than erosion. Many different types of valleys are described by geographers, using terms that may be global in use or else applied only locally. Valleys may arise through several different processes. Most commonly, they arise from erosion over long periods by moving water and are known as river valleys. Typically small valleys containing streams feed into larger valleys which in turn feed into larger valleys again, eventually reaching

598-405: Is a tributary valley that is higher than the main valley. They are most commonly associated with U-shaped valleys, where a tributary glacier flows into a glacier of larger volume. The main glacier erodes a deep U-shaped valley with nearly vertical sides, while the tributary glacier, with a smaller volume of ice, makes a shallower U-shaped valley. Since the surfaces of the glaciers were originally at

644-413: Is associated with the stretching and thinning of the crust or the lithosphere . This type of tectonics is found at divergent plate boundaries, in continental rifts , during and after a period of continental collision caused by the lateral spreading of the thickened crust formed, at releasing bends in strike-slip faults , in back-arc basins , and on the continental end of passive margin sequences where

690-421: Is formed in the process of sea-floor spreading ; transform , where plates slide past each other, and convergent , where plates converge and lithosphere is "consumed" by the process of subduction . Convergent and transform boundaries are responsible for most of the world's major ( M w > 7) earthquakes . Convergent and divergent boundaries are also the site of most of the world's volcanoes , such as around

736-501: Is only 50 meters (160 ft) deep while the main fjord is around 1,300 meters (4,300 ft) at the same point. Glaciated terrain is not the only site of hanging streams and valleys. Hanging valleys are also simply the product of varying rates of erosion of the main valley and the tributary valleys. The varying rates of erosion are associated with the composition of the adjacent rocks in the different valley locations. The tributary valleys are eroded and deepened by glaciers or erosion at

782-452: Is the study of the motions and deformations of the Earth's crust ( geological and geomorphological processes) that are current or recent in geological time . The term may also refer to the motions and deformations themselves. The corresponding time frame is referred to as the neotectonic period . Accordingly, the preceding time is referred to as palaeotectonic period . Tectonophysics is

828-488: Is the word cwm borrowed from Welsh . The word dale occurs widely in place names in the north of England and, to a lesser extent, in southern Scotland. As a generic name for a type of valley, the term typically refers to a wide valley, though there are many much smaller stream valleys within the Yorkshire Dales which are named "(specific name) Dale". Clough is a word in common use in northern England for

874-629: Is used in England and Wales to describe a wide river valley, usually with a particularly wide flood plain or flat valley bottom. In Southern England, vales commonly occur between the outcrops of different relatively erosion-resistant rock formations, where less resistant rock, often claystone has been eroded. An example is the Vale of White Horse in Oxfordshire. Some of the first human complex societies originated in river valleys, such as that of

920-519: The Latin terms for 'valley, 'gorge' and 'ditch' respectively. The German term ' rille ' or Latin term 'rima' (signifying 'cleft') is used for certain other elongate depressions on the Moon. See also: Tectonics Tectonics (from Latin tectonicus ; from Ancient Greek τεκτονικός ( tektonikós )  'pertaining to building ') are the processes that result in

966-504: The Nile , Tigris-Euphrates , Indus , Ganges , Yangtze , Yellow River , Mississippi , and arguably the Amazon . In prehistory , the rivers were used as a source of fresh water and food (fish and game), as well as a place to wash and a sewer. The proximity of water moderated temperature extremes and provided a source for irrigation , stimulating the development of agriculture . Most of

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1012-668: The first civilizations developed from these river valley communities. Siting of settlements within valleys is influenced by many factors, including the need to avoid flooding and the location of river crossing points. Numerous elongate depressions have been identified on the surface of Mars , Venus , the Moon , and other planets and their satellites and are known as valles (singular: 'vallis'). Deeper valleys with steeper sides (akin to canyons) on certain of these bodies are known as chasmata (singular: 'chasma'). Long narrow depressions are referred to as fossae (singular: 'fossa'). These are

1058-586: The foreland to a collisional belt. In plate tectonics, the outermost part of the Earth known as the lithosphere (the crust and uppermost mantle ) act as a single mechanical layer. The lithosphere is divided into separate "plates" that move relative to each other on the underlying, relatively weak asthenosphere in a process ultimately driven by the continuous loss of heat from the Earth's interior. There are three main types of plate boundaries: divergent , where plates move apart from each other and new lithosphere

1104-662: The A303, ignores the A30 and slips down on winding country roads past Bow Brook and Gibbs Marsh towards Sherborne"; while she placed the western boundary outside the Stour watershed "south of Sherborne down Dancing Hill, across the A352 and pick up the line of the River Yeo towards Beer Hackett, Yetminster and Chetnole". The River Stour flows out of the vale at Blandford Forum in the southeast,

1150-466: The Pacific Ring of Fire . Most of the deformation in the lithosphere is related to the interaction between plates at or near plate boundaries. The latest studies, based on the integration of available geological data, and satellite imagery and Gravimetric and magnetic anomaly datasets have shown that the crust of the Earth is dissected by thousands of different types of tectonic elements which define

1196-524: The Scandinavian ice sheet during the various ice ages advanced slightly uphill against the lie of the land. As a result, its meltwaters flowed parallel to the ice margin to reach the North Sea basin, forming huge, flat valleys known as Urstromtäler . Unlike the other forms of glacial valleys, these were formed by glacial meltwaters. Depending on the topography , the rock types , and the climate ,

1242-554: The Stour and neighbouring valleys of the Yeo to the west and Brue to the north. A narrower definition places the limits of the vale close to the county boundary and villages like Bourton , where the landscape transitions to hillier greensand, limestone and sandstone geology. In her book on the Blackmore Vale, Hilary Townsend described the northern boundary as "above Gillingham, through Motcombe to Queen Oak and Bourton, then crosses

1288-511: The actual valley bottom is unclear. Trough-shaped valleys occur mainly in periglacial regions and in tropical regions of variable wetness. Both climates are dominated by heavy denudation. Box valleys have wide, relatively level floors and steep sides. They are common in periglacial areas and occur in mid-latitudes, but also occur in tropical and arid regions. Rift valleys, such as the Albertine Rift and Gregory Rift are formed by

1334-419: The crust or the lithosphere. This type of tectonics is found along oceanic and continental transform faults which connect offset segments of mid-ocean ridges . Strike-slip tectonics also occurs at lateral offsets in extensional and thrust fault systems. In areas involved with plate collisions strike-slip deformation occurs in the over-riding plate in zones of oblique collision and accommodates deformation in

1380-463: The drier strips of limestone, whereas the more poorly draining clays (which comprise the greater bulk of the area) are more sparsely populated, supporting mostly small farms, dotted across the vale. Due to the clay soils, land use is predominantly dairy farming. Until it was closed in 1998, Sturminster Newton livestock market was the busiest weekly livestock market in Britain. The vale, in particular

1426-509: The expansion of the Earth 's crust due to tectonic activity beneath the Earth's surface. There are many terms used for different sorts of valleys. They include: Similar geographical features such as gullies , chines , and kloofs , are not usually referred to as valleys. The terms corrie , glen , and strath are all Anglicisations of Gaelic terms and are commonly encountered in place-names in Scotland and other areas where Gaelic

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1472-443: The flow slower and both erosion and deposition may take place. More lateral erosion takes place in the middle section of a river's course, as strong currents on the outside of its curve erode the bank. Conversely, deposition may take place on the inside of curves where the current is much slacker, the process leading to the river assuming a meandering character. In the lower valley, gradients are lowest, meanders may be much broader and

1518-427: The land surface or rejuvenation of the watercourse as a result for example of a reduction in the base level to which the river is eroded, e.g. lowered global sea level during an ice age . Such rejuvenation may also result in the production of river terraces . There are various forms of valleys associated with glaciation. True glacial valleys are those that have been cut by a glacier which may or may not still occupy

1564-463: The ocean or perhaps an internal drainage basin . In polar areas and at high altitudes, valleys may be eroded by glaciers ; these typically have a U-shaped profile in cross-section, in contrast to river valleys, which tend to have a V-shaped profile. Other valleys may arise principally through tectonic processes such as rifting . All three processes can contribute to the development of a valley over geological time. The flat (or relatively flat) portion of

1610-436: The power of the moving ice. In places, a rock basin may be excavated which may later be filled with water to form a ribbon lake or else by sediments. Such features are found in coastal areas as fjords . The shape of the valley which results from all of these influences may only become visible upon the recession of the glacier that forms it. A river or stream may remain in the valley; if it is smaller than one would expect given

1656-446: The same elevation , the shallower valley appears to be 'hanging' above the main valley. Often, waterfalls form at or near the outlet of the upper valley. Hanging valleys also occur in fjord systems underwater. The branches of Sognefjord are much shallower than the main fjord. The mouth of Fjærlandsfjord is about 400 meters (1,300 ft) deep while the main fjord nearby is 1,200 meters (3,900 ft) deep. The mouth of Ikjefjord

1702-550: The shoulders are quite low (100–200 meters above the bottom). Many villages are located here (esp. on the sunny side) because the climate is very mild: even in winter when the valley's floor is filled with fog, these villages are in sunshine . In some stress-tectonic regions of the Rocky Mountains or the Alps (e.g. Salzburg ), the side valleys are parallel to each other, and are hanging . Smaller streams flow into rivers as deep canyons or waterfalls . A hanging valley

1748-849: The size of its valley, it can be considered an example of a misfit stream . Other interesting glacially carved valleys include: A tunnel valley is a large, long, U-shaped valley originally cut under the glacial ice near the margin of continental ice sheets such as that now covering Antarctica and formerly covering portions of all continents during past glacial ages. Such valleys can be up to 100 km (62 mi) long, 4 km (2.5 mi) wide, and 400 m (1,300 ft) deep (its depth may vary along its length). Tunnel valleys were formed by subglacial water erosion . They once served as subglacial drainage pathways carrying large volumes of meltwater. Their cross-sections exhibit steep-sided flanks similar to fjord walls, and their flat bottoms are typical of subglacial glacial erosion. In northern Central Europe,

1794-476: The south and east, the vale is clearly delimited by the steep escarpments of two areas of higher chalk downland, the Dorset Downs to the south, and Cranborne Chase to the east. To the north and west, the definitions of the vale are more ambiguous, as the landscape changes more gradually around the upper reaches of the Stour and its tributaries. One definition places the boundary along the watershed between

1840-462: The structure and properties of the Earth's crust and its evolution through time. The field of planetary tectonics extends the concept to other planets and moons. These processes include those of mountain-building , the growth and behavior of the strong, old cores of continents known as cratons , and the ways in which the relatively rigid plates that constitute the Earth's outer shell interact with each other. Principles of tectonics also provide

1886-576: The study of the physical processes associated with deformation of the crust and mantle from the scale of individual mineral grains up to that of tectonic plates. Seismotectonics is the study of the relationship between earthquakes, active tectonics, and individual faults in a region. It seeks to understand which faults are responsible for seismic activity in an area by analysing a combination of regional tectonics, recent instrumentally recorded events, accounts of historical earthquakes, and geomorphological evidence. This information can then be used to quantify

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1932-403: The subdivision into numerous smaller microplates which have amalgamated into the larger Plates. Salt tectonics is concerned with the structural geometries and deformation processes associated with the presence of significant thicknesses of rock salt within a sequence of rocks. This is due both to the low density of salt, which does not increase with burial, and its low strength. Neotectonics

1978-407: The upper valley, the stream will most effectively erode its bed through corrasion to produce a steep-sided V-shaped valley. The presence of more resistant rock bands, of geological faults , fractures , and folds may determine the course of the stream and result in a twisting course with interlocking spurs . In the middle valley, as numerous streams have coalesced, the valley is typically wider,

2024-407: The valley at the present day. Such valleys may also be known as glacial troughs. They typically have a U-shaped cross-section and are characteristic landforms of mountain areas where glaciation has occurred or continues to take place. The uppermost part of a glacial valley frequently consists of one or more 'armchair-shaped' hollows, or ' cirques ', excavated by the rotational movement downslope of

2070-938: The village of Marnhull ("Marlott"), is the opening backdrop for Thomas Hardy 's Tess of the D'Urbervilles ; he also lived and wrote in Sturminster Newton for a time. William Barnes the poet also lived in Sturminster Newton. Douglas Adams and Robert Boyle lived in Stalbridge for part of their lives. The New Blackmore Vale Magazine is named for the area. Settlements in the vale include: [REDACTED] Media related to Blackmore Vale at Wikimedia Commons River valley At lower latitudes and altitudes, these glacially formed valleys may have been created or enlarged during ice ages but now are ice-free and occupied by streams or rivers. In desert areas, valleys may be entirely dry or carry

2116-414: Was once widespread. Strath signifies a wide valley between hills, the floor of which is either level or slopes gently. A glen is a river valley which is steeper and narrower than a strath. A corrie is a basin-shaped hollow in a mountain. Each of these terms also occurs in parts of the world formerly colonized by Britain . Corrie is used more widely by geographers as a synonym for (glacial) cirque , as

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