Glacial deposits and erratics in the Fremington area. Note that the till cover extends over the 60m contour. It is therefore not surprising that "high level erratics" are found at even greater altitudes elsewhere on the Devon coasts.
Been waiting for this for some time. A very comprehensive and interesting summary. I'm intrigued by the suggestion that glacier ice "approached" the North Devon coast on at least three occasions from the Bristol Channel, and probably crossed it more than once. The authors are in no doubt about the presence of glacial deposits in the Fremington area. I would have liked a more careful consideration of the ice rafting hypothesis in the section where they talk about erratic boulders. They say that the rivers that cut the deep river valleys were graded to low, cold period sea levels, but if that was the case you cannot have high sea levels with ice rafting of erratics when conditions were of "full glacial" status. You can't have your cake and eat it.
Anyway, I'll give this useful article greater consideraton on another occasion.
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Bennett, J.A., Cullingford, R.A., Gibbard, P.L., Hughes, P.D. and Murton, J.B. 2024. The Quaternary Geology of Devon. Proceedings of the Ussher Society, 15, 84-130.
Bennett, J.A., Cullingford, R.A., Gibbard, P.L., Hughes, P.D. and Murton, J.B. 2024. The Quaternary Geology of Devon. Proceedings of the Ussher Society, 15, 84-130.
https://ussher.org.uk/journal/catalogue/volume-15-part-3-2024
Throughout the 2.6 My of the Quaternary, Devon has occupied a critical position with respect to the evolution of Britain in that it lies close to the North Atlantic Ocean between the southern coast of the Bristol Channel and the northern coast of the English Channel. This setting results in the area being highly sensitive to climatic and environmental change. Although the county lies beyond the general limit of the major glaciations of the last 0.5 My, it was impacted by glacial ice and its associated meltwater that approached the north coast on at least three occasions. Glaciers also left deposits on the Bristol Channel floor and potentially locally on Dartmoor and possibly Exmoor. Ice-rafting of erratic rocks also occurred. Nevertheless, the whole region has been repeatedly subjected to severe cold-climate, periglacial conditions for much of Quaternary time. Under cold periods frost- dominated climates have driven the formation of a thick carapaces of slope-derived debris (head deposits), with wind erosion shaping the tors characteristic of the high moorlands. At the same time deep river valleys have been carved by continual severe seasonal snow meltwater, the streams transporting weathered rock derived from the steep slopes. The rivers that cut these valleys were graded to low, cold period sea levels, and their valleys frequently include multiple terrace accumulations, the highest of which date from the Middle Pleistocene. Apart from the Late-glacial open vegetation and Holocene blanket peatland, evidence of earlier warm-climate conditions also occur, but are limited in comparison to the cold-climate accumulations. Past and present interglacial (temperate) deposits are also known from the county. They include not only river deposits, but also cave infillings and high sea-level, fossil beaches, often including fossil evidence. Coastal erosional landforms such as wave-cut platforms and cliff formations are commonly found, and submerged offshore examples are also known, particularly from the English Channel coast. Despite all this evidence, its fragmentary nature means that the record of events in the region is both limited and intriguing. The advent of numerical age determination and other modern analytical methods have improved knowledge of the timing of some events and provenance of materials in the region, but much more work is required to fill in the substantial gaps in current knowledge.
Abstract
Throughout the 2.6 My of the Quaternary, Devon has occupied a critical position with respect to the evolution of Britain in that it lies close to the North Atlantic Ocean between the southern coast of the Bristol Channel and the northern coast of the English Channel. This setting results in the area being highly sensitive to climatic and environmental change. Although the county lies beyond the general limit of the major glaciations of the last 0.5 My, it was impacted by glacial ice and its associated meltwater that approached the north coast on at least three occasions. Glaciers also left deposits on the Bristol Channel floor and potentially locally on Dartmoor and possibly Exmoor. Ice-rafting of erratic rocks also occurred. Nevertheless, the whole region has been repeatedly subjected to severe cold-climate, periglacial conditions for much of Quaternary time. Under cold periods frost- dominated climates have driven the formation of a thick carapaces of slope-derived debris (head deposits), with wind erosion shaping the tors characteristic of the high moorlands. At the same time deep river valleys have been carved by continual severe seasonal snow meltwater, the streams transporting weathered rock derived from the steep slopes. The rivers that cut these valleys were graded to low, cold period sea levels, and their valleys frequently include multiple terrace accumulations, the highest of which date from the Middle Pleistocene. Apart from the Late-glacial open vegetation and Holocene blanket peatland, evidence of earlier warm-climate conditions also occur, but are limited in comparison to the cold-climate accumulations. Past and present interglacial (temperate) deposits are also known from the county. They include not only river deposits, but also cave infillings and high sea-level, fossil beaches, often including fossil evidence. Coastal erosional landforms such as wave-cut platforms and cliff formations are commonly found, and submerged offshore examples are also known, particularly from the English Channel coast. Despite all this evidence, its fragmentary nature means that the record of events in the region is both limited and intriguing. The advent of numerical age determination and other modern analytical methods have improved knowledge of the timing of some events and provenance of materials in the region, but much more work is required to fill in the substantial gaps in current knowledge.
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