Aymestry Limestone
The Aymestry Limestone is a fossiliferous limestone of Gorstian age (Upper Silurian) deposited in a warm shallow sea near the eastern margin of the Iapetus Ocean. It occurs in England in the Ludlow Group, between the Upper and Lower Ludlow Shales.[1] It derives its name from Aymestrey (sic), Herefordshire, where it may be seen on both sides of the River Lugg. It is well developed in the neighbourhood of Ludlow (it is sometimes called the Ludlow limestone) and occupies a similar position in the Ludlow shales at Woolhope, the Abberley Hills, May Hill and the Malvern Hills.[2]
| Aymestry Limestone Stratigraphic range: Silurian | |
|---|---|
| Type | Formation |
| Underlies | Upper Ludlow Shales Group |
| Overlies | Lower Ludlow Shales Group |
| Thickness | Up to 48 m (157 ft) |
| Lithology | |
| Primary | Limestone |
| Other | Mudstone, sandstone |
| Location | |
| Region | Welsh Marches, West Midlands, Coalbrookdale & Malvern Hills |
| Country |  United Kingdom |
| Type section | |
| Named for | Aymestrey |
Description
In lithological character, this limestone varies greatly; in one place it is a dark grey, somewhat crystalline limestone, elsewhere it passes into a flaggy, earthy or shaly condition, or even into a mere layer of nodules. When well developed it may reach 50 ft. in thickness in beds of from 1 to 5 ft.; in this condition it naturally forms a conspicuous feature in the landscape because it stands out by its superior hardness from the soft shales above and below.[2]
The most common fossil is Pentamerus knightii, which is extremely abundant in places. Other brachiopods, corals and trilobites are present, and are similar to those found in the Wenlock limestone.[2]
References
- "Aymestry Limestone Formation". The BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved 20 February 2016.
- Chisholm 1911.
Further reading
- A P Baggs; G C Baugh; D C Cox; Jessie McFall; P A Stamper (1998), "Introduction", in C R J Currie (ed.), A History of the County of Shropshire: Volume 10: Munslow Hundred (part), The Liberty and Borough of Wenlock, Institute of Historical Research, pp. 1–6, retrieved 22 March 2013
- The Silurian in Shropshire
External links
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Aymestry Limestone". Encyclopædia Britannica. 3 (11th ed.). Cambridge University Press. pp. 73–74.- Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 31 July 2014. Retrieved 8 July 2014.