| Computer Code: |
LT |
Preferred Map Code: |
LT |
| Status Code: |
Full |
| Age range: |
Brigantian Substage (CX)
— Brigantian Substage (CX) |
| Lithological Description: |
At the type locality the member is dominated by a volcanic breccia (agglomerate) with clasts, including some limestone, up to 13 cm diameter (Stevenson and Gaunt, 1971). In the Longstone Edge boreholes (e.g. SK 2144 7367) the member comprises one to three leaves of grey and green banded tuff with some limestone grains. The thickest development in these boreholes is associated with a well-sorted tuff, with coarser bands of fine lapilli (Aitkenhead et al., 1985). In the Eyam Borehole the member is a 1.1 m thick, fine-grained, grey-green, pyritic tuff (Dunham, 1973). |
| Definition of Lower Boundary: |
The tuff at the base of the member is underlain by dark to medium grey limestones of the Monsal Dale Limestone Formation. |
| Definition of Upper Boundary: |
The tuff at the top of the member is overlain by dark grey cherty limestones of the Monsal Dale Limestone Formation. |
| Thickness: |
Maximum thickness of in excess of 30 m to the north-east of Litton. |
| Geographical Limits: |
The member can be traced from Tideswell Moor (SK 152 766), Litton (SK 168 751), Cressbrook Dale (SK 172 749) and Wardlow Hay Cop (SK 180 738). |
| Parent Unit: |
Monsal Dale Limestone Formation (MO)
|
| Previous Name(s): |
Litton Tuff [Obsolete Name and Code: Use LT]
(-3541)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Slopes north and east of Litton, includes roadside exposures of 3.6 m of brown-weathered tuff from the upper part of the member. Stevenson and Gaunt, 1971. |
| Reference(s): |
| Stevenson, I P and Gaunt, G D, 1971. Geology of the country around Chapel-en-le-Frith. Memoir of the Geological Survey of Great Britain, England and Wales, Sheet 99. |
| Aitkenhead, N, Chisholm, J I, and Stevenson, I P. 1985. Geology of the country around Buxton, Leek and Bakewell. Memoir of the British Geological Survey, England and Wales Sheet 111. |
| Dunham, K C. 1973. A recent deep borehole near Eyam, Derbyshire. Nature Physical Science, Vol. 241, 84-85. |
| Walters, S G and Ineson, P R. 1981. A review of the distribution of and the correlation of igneous rocks in Derbyshire, England. Mercian Geologist, Vol. 8, 81-132. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E111
E099
|
