Computer Code: |
HCG |
Preferred Map Code: |
notEntered |
Status Code: |
Full |
Age range: |
Ediacaran Period (AD)
— Ediacaran Period (AD) |
Lithological Description: |
A massive conglomerate with subordinate pebbly sandstone. The conglomerate is generally composed of clasts of white quartzite in a red-brown sandstone matrix. |
Definition of Lower Boundary: |
Taken at the relatively sharp, but conformable contact with the underlying purple shaly mudstones and siltstones of the Lightspout Formation. |
Definition of Upper Boundary: |
Poorly exposed, but taken at the conformable transition from conglomerate and coarse pebbly sandstone into the purple siltstones and sandstones of the main part of the Portway Formation. |
Thickness: |
Up to 18 m thick. |
Geographical Limits: |
Welsh Borderlands, Church Stretton and the Long Mynd. |
Parent Unit: |
Portway Formation (PWG)
|
Previous Name(s): |
Huckster Conglomerate [Obsolete Code: Use HCG]
(YSPH)
|
Alternative Name(s): |
Narnells Grit
|
Stratotypes: |
Partial Type Section |
Huxter Stone, 135 m south southeast of Handless Farm [SO 397 900]. Greig et al., 1968. |
Reference(s): |
Greig D C, Wright, J E, Hains, B A and Mitchell, G H. 1968. Geology of the country around Church Stretton, Craven Arms, Wenlock Edge and Brown Clee. Memoir of the Geological Survey, Sheet 166 (England and Wales). (London: H.M.S.O.). 379pp. |
Lapworth C and Watts W W. 1910. Shropshire. 739-769 in Geology in the field; the Jubilee Volume of the Geologists' Association (1858-1908). Monckton H W and Herries R S (editors). (London: Edward Stanford). |
Pauley J C. 1991. A revision of the stratigraphy of the Longmyndian Supergroup, Welsh Borderland, and of its relationship to the Uriconian volcanic complex. Geological Journal, Vol. 26, 167-183. |
Pauley J C. 1990. The Longmyndian Supergroup and related Precambrian sediments of England and Wales. 5-27 in Avalonian and Cadomain geology of the North Atlantic. Strachan R A and Taylor G K (editors). (Glasgow: Blackie). |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
E166
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