Geological significance of dolyhir and nash scar limestone

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Geological significance of dolyhir and nash scar limestone

Sedimentary Click to enlarge. Overview Silurian rocks in Herefordshire and Worcestershire are used as markers for this period of earth history throughout the world.

The rocks are also famous for their diversity and richness of fossils, and this has led to accurate sub-divisions of the period being devised: All four of these time frames are represented the two counties. In Worcestershire the outcrop of Silurian rocks generally follows a north-south linear trend, beginning just north of the Malvern Hills and continuing along the central and eastern half of the Teme Valley, before splitting into two outcrops around Abberley.

The Nash Scar Limestone found in northwest Herefordshire is thought to be contemporaneous with the Woolhope Limestone.

Publications — University of Leicester

Lithology Woolhope Limestone The unit conformably succeeds the May Hill Sandstone Group and is characterised by pale grey, nodular limestone and calcareous mudstone which weathers buff and olive-grey.

The Woolhope Limestone has a restricted fauna, dominated by tabulate corals and brachiopods. Broken shell debris is common in the unit, suggesting deposition in shallow water with vigorous wave action. It is a crystalline, fossiliferous limestone which developed in proximity to the Church Stretton Fault System.

This created an area of shallow water further west than the other outcrops of limestone of this age. The lower boundary unconformably overlies the Folly Sandstone.The Nash Scar Limestone and the Dolyhir Limestone may be in part of Ce age, or there may have been non-deposition.

As these algal limestones accumulated in very shallow water, we can at least infer that deep water is unlikely to have covered this region in Ce time, and the lack of clastic sediments supports the suggestion that the area was.

(d) Nash Scar and Old Radnor (Fig. 3, col. 5) The Nash Scar Limestone overlies upper Llandovery beds of C1_~ age (Ziegler & others, b) and underlies mudstones containing graptolites indicating the late Wenlock C.

lundgreni zone.

Geological significance of dolyhir and nash scar limestone

The Nash Scar Limestone (also known as the Dolyhir Limestone) found in northwest Herefordshire within the area of the unmapped BGS Knighton Sheet () is believed to be equivalent in age to the Woolhope Limestone.

The geological significance of the Dolyhir and Nash Scar limestone (Silurian) of the Welsh Borderland Introduction and History Ther regions of Old Radnor and Presteigne (Fig.

1), found on the outskirts of Hertfordshire and Powys, are home to two small inliers containing a mammoth unit of limestones of the early Silurian age, thick and distinctive in their form. National Museum of Wales Geological Series, 10, pp.

Cardiff. Vannier, J.M.C., Siveter, D.J. & Schallreuter, R.E.L. The composition and palaeogeographical significance of the Ordovician ostracode faunas of Southern Britain, Baltoscandia and Ibero-Amorica. Palaeontology, 32, Hansch, W. & Siveter, D.J. Exposed Units: Folly Sandstone, Nash Scar Limestone, Coalbrookdale Formation.

This is a large quarry in Nash Scar Limestone and Folly Sandstone with faulting associated with the Church Stretton Fault System. Huge cliffs of crystalline limestone show corals, bryozoans and brachiopod fossils.

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