Hemlock Stone facts for kids
Quick facts for kids Hemlock Stone |
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| Himlack Stone | |
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 Location in Nottinghamshire
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| Location | Stapleford Hill, Stapleford, Nottinghamshire, England |
| Coordinates | 52°56′34.93″N 1°15′29.14″W / 52.9430361°N 1.2580944°W |
The Hemlock Stone or Himlack Stone is an inselberg on Stapleford Hill at Stapleford, Nottinghamshire, England.
Geology
The Hemlock Stone is an outcrop of New Red Sandstone, deposited more than 200 million years ago in the Triassic Period. Approximately 28 feet (8.5 m) high, it is formed of a layer of Nottingham Castle Sandstone overlying a layer of Lenton Sandstone. Both layers are members of the Sherwood Sandstone Group. The Nottingham Castle Sandstone is a medium- to coarse-grained sandstone in which the grains are strongly cemented together by baryte. The Lenton Sandstone is very fine-grained but less well cemented together. As a result, the lower part of the stone is more vulnerable to erosion than the upper part, resulting in differential erosion that has given the inselberg its current "waisted" shape.
There are two geological theories as to what removed the surrounding sandstone layers of which the inselberg was once a part. In the 18th century the antiquarian William Stukeley (1687–1765) proposed that it had been left by quarrying of the surrounding stone. Certainly there are signs of past quarrying on and around Stapleford Hill. In 1908 the Ordnance Geological Survey (OGS) propounded that it was the result purely of natural differential erosion, particularly by ice in the Quaternary glaciation. But the British Geological Survey, the OGS's modern successor, now supports Stukeley's theory.
Nevertheless, research continues as recently as October 2015 with the Nottingham University's Geospatial Institute undertaking further study as part of their “Three Stones Project”. Since, in the past, laser mapping has not completely covered the stone, they have employed a drone equipped with laser mapping cameras.
Black grime coats the Nottingham Castle Sandstone that forms the upper part of the inselberg, but there is none on the Lenton Sandstone below. The grime is from industrial air pollution before the UK started to restrict air pollution, and illustrates the fact that the upper layer erodes much more slowly than the layer below. wind erosion is continuing and will eventually destabilise the inselberg. The stone is now protected by an iron fence, next to which is a sign to explain the stone to visitors.
Links
Images for kids
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Eroded layers of Lenton Sandstone in the lower part of the Hemlock Stone
