| 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): |
| 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. |
| 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: HMSO.) 379pp. |
| 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
|
