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arborescent structures, extend upwards from the hedge and are relatively constant in height at about 4–5 cm, although somewhat shorter near the lens edges. In most cases the lenses contain only a single layer of the landscape, but two, or exceptionally three layers may be developed, known as double and triple landscape marble respectively, each growing up from the crest of the underlying layer.
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The lenses are typically between 3 and over 20 centimetres thick and are up to 3 metres across. Within each lens there is a basal convex upward layer from which the landscape rises. The 'hedge' layer is about 5 millimetres thick, marked at the top by many small bumps. The 'trees',
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Although described as a variety of Cotham Marble, and often found in association with it, this limestone has a different origin. It consists of thin limestone flakes often set almost on edge within a sandy limestone. These are interpreted to have a mechanical origin as a form of mud-flake
104:. They occur as lenses within the upper part of the Cotham Member. The marble is widely but patchily developed within the Cotham Member in its outcrop that extends from Glamorgan in South Wales, through the Bristol area to the coast of southeast Devon.
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The marble is too soft for external use and has been mainly used to produce ornaments for display and as inlay in furnishings, such as tables and chimney pieces.
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The formation of the unusual structures in Cotham Marble has been ascribed to a number of causes. The earliest explanations were all inorganic, including
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deposition and the effect of gas bubbles rising through the sediment. The interpretation that Cotham Marble is a stromatolite of
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88:. On cut and polished faces the stone has the appearance of a landscape, complete with ploughed fields, trees, and hedges.
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167:"The lithostratigraphy of the Penarth Group (Late Triassic) of the Severn Estuary area"
249:"Algal tuft structures in stromatolites from the Upper Triassic of South-west England"
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origin was first proposed in 1961 and since has been confirmed by later work.
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84:. This limestone was used for ornamental purposes, particularly during the
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The beds known as Cotham Marble form part of the Cotham Member of the
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223:"Algal growths in the Rhaetic Cotham Marble of Southern England"
334:. Sterling Publishing Company, Inc. p. 236.
76:, possibly extending to the south coast in east
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280:. English Heritage. August 2011. p. 14
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301:The Buildings of England: Devon, Volume 5
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34:Top surface of a layer of Cotham Marble
304:. Yale University Press. p. 213.
247:Mayall M.J. & Wright V.P. (1981).
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298:Cherry, B. & Pevsner N. (1991).
80:. It is named after Cotham House in
16:Limestone variety from Great Britain
23:An example of Cotham Marble in the
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274:"A Building Stone Atlas of Avon"
174:Geoscience in South-West England
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196:Cabinet of Curiosities
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25:Natural History Museum
358:Cotham Marble at the
278:Strategic Stone Study
165:Gallois R.W. (2009).
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221:Hamilton D. (1961).
72:in the area around
383:Geology of England
361:Virtual Microscope
98:Lilstock Formation
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68:and southwestern
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393:Triassic geology
388:Geology of Wales
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192:"Cotham Marble"
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282:. Retrieved
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200:. Retrieved
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128:Crazy Cotham
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49:(uppermost
372:Categories
284:2013-06-09
202:2013-06-09
149:References
118:evaporitic
92:Occurrence
378:Limestone
112:Formation
60:from the
58:limestone
364:website.
328:(2009).
180:: 71–84.
51:Triassic
47:Rhaetian
398:Bristol
331:Fossils
135:breccia
74:Bristol
70:England
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252:(PDF)
226:(PDF)
170:(PDF)
122:algal
78:Devon
66:Wales
336:ISBN
306:ISBN
141:Uses
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