Editing Quaternary geology and geomorphology of the area around Kisdon, upper Swaledale - an excursion

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Many of the small-scale landforms are classical for their type and provide detailed evidence of the direction of ice movement across the region, the pattern of ice wastage, the response of rivers and oversteepened slopes to changes of climate over the past c. 15 000 years and the effects of human activity on river processes. Glaciofluvial landforms include a variety of glacial '''meltwater channels''' southwest of Keld, '''kames''' and '''kettle holes''' around Angram and Thwaite and '''kame terraces''' west of Muker. Evidence for climatically driven changes of river activity include a debris flow fan at Hartlakes, and river terraces along the Swale upstream of West Stonesdale Beck. Landforms produced by slope failure include a deep rotational slip at Hooker Mill, a massive debris slide on the northwest side of Kisdon, a massive debris flow at Usha Gap and a block glide at Birk Hill. In the upper part of Skeb Skeugh fine-grained lake sediments below the valley bottom preserve the record of Devensian Lateglacial and Holocene vegetational change, soil development and slope stability. In addition, river landforms show the effects of rock control, of human activity in determining sediment loads, and intrinsic within-channel processes resulting in the formation of large-scale boulder bedforms. The river terraces upstream of Kisdon Force have an extent and elevation determined by rock hardness. Those around Thwaite show the effects of reduced discharge of the present rivers relative to the discharges of the rivers that formed the main valley bottom floodplain slopes, while the impressive array of valley bottom terraces south of Hartlakes are the product of within-channel processes enhanced by sediment yield from the local lead mines.
 
Many of the small-scale landforms are classical for their type and provide detailed evidence of the direction of ice movement across the region, the pattern of ice wastage, the response of rivers and oversteepened slopes to changes of climate over the past c. 15 000 years and the effects of human activity on river processes. Glaciofluvial landforms include a variety of glacial '''meltwater channels''' southwest of Keld, '''kames''' and '''kettle holes''' around Angram and Thwaite and '''kame terraces''' west of Muker. Evidence for climatically driven changes of river activity include a debris flow fan at Hartlakes, and river terraces along the Swale upstream of West Stonesdale Beck. Landforms produced by slope failure include a deep rotational slip at Hooker Mill, a massive debris slide on the northwest side of Kisdon, a massive debris flow at Usha Gap and a block glide at Birk Hill. In the upper part of Skeb Skeugh fine-grained lake sediments below the valley bottom preserve the record of Devensian Lateglacial and Holocene vegetational change, soil development and slope stability. In addition, river landforms show the effects of rock control, of human activity in determining sediment loads, and intrinsic within-channel processes resulting in the formation of large-scale boulder bedforms. The river terraces upstream of Kisdon Force have an extent and elevation determined by rock hardness. Those around Thwaite show the effects of reduced discharge of the present rivers relative to the discharges of the rivers that formed the main valley bottom floodplain slopes, while the impressive array of valley bottom terraces south of Hartlakes are the product of within-channel processes enhanced by sediment yield from the local lead mines.
  
Meltwater channels, '''drift''' tails, '''drumlins''' and striations provide the main evidence that glaciation of the region was from the west, and an explanation for the anomalous valley pattern of the Swale and Skeb Skeugh and the origin of Kisdon hill. Meltwater channels indicate that prior to the final melting of this ice sheet, drainage was through Skeb Skeugh and the area between Keld and Hartlakes was an interfluve between the Swale and Swinner Gill. The present valley between these points is ascribed to glacial erosion in response to structural weakness and relatively high glacier energy determined by a steep ice-surface gradient. The kame terraces at Muker indicate a temporary ice-dammed lake between an ice lobe in the Swale valley and a lobe in the Muker Beck valley, and dead ice topography around Angram indicates local ice stagnation. This episode of glaciation was during the Dimlington Stadial (26&nbsp;000–13&nbsp;000 <sup>14</sup>C yrs BP) of the Late Devensian Glaciation and ice wastage across the region occurred about 14&nbsp;000 <sup>14</sup>C yrs BP.
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Meltwater channels, drift tails, drumlins and striations provide the main evidence that glaciation of the region was from the west, and an explanation for the anomalous valley pattern of the Swale and Skeb Skeugh and the origin of Kisdon hill. Meltwater channels indicate that prior to the final melting of this ice sheet, drainage was through Skeb Skeugh and the area between Keld and Hartlakes was an interfluve between the Swale and Swinner Gill. The present valley between these points is ascribed to glacial erosion in response to structural weakness and relatively high glacier energy determined by a steep ice-surface gradient. The kame terraces at Muker indicate a temporary ice-dammed lake between an ice lobe in the Swale valley and a lobe in the Muker Beck valley, and dead ice topography around Angram indicates local ice stagnation. This episode of glaciation was during the Dimlington Stadial (26 000–13 000 <sup>14</sup>C yrs BP) of the Late Devensian Glaciation and ice wastage across the region occurred about 14 000 <sup>14</sup>C yrs BP.
  
Pollen from the lake sediments in the upper section of Skeb Skeugh indicates that tundra vegetation colonized the region during the Windermere Interstadial (13&nbsp;000–11&nbsp;000 <sup>14</sup>C yrs BP), but that this vegetation broke down during the severe climate of the Loch Lomond Stadial (11&nbsp;000–10&nbsp;000 <sup>14</sup>C yrs BP). The mineral content of these lake sediments indicates that accelerated mass movement took place on the slopes during the Loch Lomond Stadial, resulting in the formation of the debris slide on the northwest side of Kisdon. It is probable that the debris flow at Usha Gap and the high fan at the mouth of Swinner Gill also formed at this time.
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Pollen from the lake sediments in the upper section of Skeb Skeugh indicates that tundra vegetation colonized the region during the Windermere Interstadial (13 000–1 1 000 <sup>14</sup>C yrs BP), but that this vegetation broke down during the severe climate of the Loch Lomond Stadial (11 000–10 000<sup>14</sup>C yrs BP). The mineral content of these lake sediments indicates that accelerated mass movement took place on the slopes during the Loch Lomond Stadial, resulting in the formation of the debris slide on the northwest side of Kisdon. It is probable that the debris flow at Usha Gap and the high fan at the mouth of Swinner Gill also formed at this time.
  
During the Holocene (10&nbsp;000 <sup>14</sup>C yrs BP to present) vegetation cover returned including extensive woodland, and the rate and magnitude of geomorphological processes was reduced. However, thick glaciogenic sediments and steep valley-side and valley-bottom slopes maintained a paraglacial regime, and relatively high levels of river and slope activity resulted in the formation of important and distinctive landforms. Hooker Mill rotational slip occurred during the early Holocene damming a long narrow lake in the upper part of Skeb Skeugh, and the block glide at Birk Hill continues to move in response to river erosion. River activity has resulted in incision and the formation of river terraces of a variety of origins in different parts of the region, but most significantly, the introduction of mining waste during the 19th century increased the scale and rate of development of these landforms in the section of the Swale downstream of Hartlakes.
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During the Holocene (10 000 <sup>14</sup>C yrs BP to present) vegetation cover returned including extensive woodland, and the rate and magnitude of geomorphological processes was reduced. However, thick glaciogenic sediments and steep valley-side and valley-bottom slopes maintained a paraglacial regime, and relatively high levels of river and slope activity resulted in the formation of important and distinctive landforms. Hooker Mill rotational slip occurred during the early Holocene damming a long narrow lake in the upper part of Skeb Skeugh, and the block glide at Birk Hill continues to move in response to river erosion. River activity has resulted in incision and the formation of river terraces of a variety of origins in different parts of the region, but most significantly, the introduction of mining waste during the 19th century increased the scale and rate of development of these landforms in the section of the Swale downstream of Hartlakes.
  
 
For further details see Rose (1980), Rose & Pounder in Boardman (1981, 1985), Rose & Mitchell (1989) and Pounder (1989).
 
For further details see Rose (1980), Rose & Pounder in Boardman (1981, 1985), Rose & Mitchell (1989) and Pounder (1989).

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