The BGS Lexicon of Named Rock Units — Result Details

Lower Miller's Dale Lava Member

Computer Code: LMB Preferred Map Code: LMB
Status Code: Full
Age range: Asbian Substage (CR) — Asbian Substage (CR)
Lithological Description: Olivine basalt, usually very amygdaloidal with calcite-zeolite-and chlorite-filled vesicles. The central parts of flows may be non-vesicular. The lava is typically very weathered. Intervening beds of clay, tuff and limestone are locally present.
Definition of Lower Boundary: The base of the Lower Miller's Dale Lava Member, evident at Tideswell Dale (SK 154 740), is rubbly, resting directly upon about 1 m of red clay with columnar or prismatic structures up to 6 cm in diameter, possibly weathered basalt, believed to rest upon thermally altered limestone of the Bee Low Limestone Formation.(Waters, 2003).
Definition of Upper Boundary: Vesicular lava of the Lower Miller's Dale Lava Member is overlain by limestone of the Miller's Dale Limestone Member.
Thickness: About 30 m thick at Wormhill (SK 123 741), decreasing in thickness rapidly to the north.
Geographical Limits: Northern parts of the Peak District inlier, south-east of a line between Dove Holes (SK 08 77) to Ox Low (SK 12 80), and north-west of a line from Grin Low (SK 05 71) to Tideswell Dale (SK 15 73). Also, there is an isolated area to the north at Cave Dale (SK 14 82). The southern outcrops tend to be lenticular in plan.
Parent Unit: Bee Low Limestone Formation (BLL)
Previous Name(s): Lower Miller's Dale Lava (-3530)
Lower Miller's Dale Basalt (-4166)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Ashwood Dale section in a railway cutting shows full thickness of 7.62 m of vesicular lava. Aitkenhead et al., 1985. 
Reference(s):
Stephenson, D, Loughlin, S C, Millward, D, Waters, C N and Williamson, I. 2003. Carboniferous and Permian igneous rocks of Great Britain, north of the Variscan Front. Geological Conservation Review Volume 27. Joint Nature Conservation Committee: Peterborough. 374 pp. 
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. 
Waters, C N. 2003. Carboniferous and Permian igneous rocks of central England and the Welsh Borderland. In: Carboniferous and Permian Igneous Rocks of Great Britain North of the Variscan Front. (editors Stephenson D, Loughlin S C, Millward D, Waters C N, and Williamson I T.), pp. 279-316, Geological Conservation Review Series, No. 27 (JNCC). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E111 E099