Geological Society, London, Memoirs
Geological Society, London, Memoirs; 2002; v. 25;
p. 171-186;
DOI: 10.1144/GSL.MEM.2002.025.01.14
© 2002 Geological Society of London
Chapter 13 The stratigraphy of ‘Otley III’
So we turn to the work done in the twentieth century on the elucidation of the sequence and structure of the rocks of Jonathan Otley's third major subdivision of the Lakeland rocks - up to the time of the establishment of the 'Lakeland Project' in 1982, and with a preliminary forward glance to the end of the century. The rocks of 'Otley III' consist of limestones, mudstones, shales, slates, grits and conglomerates, with one substantial igneous unit, the Yarlside (or Stockdale) Rhyolite, which runs westwards from the Shap district, parallel with the strike of other rocks low in 'Mr Otley's third great physical subdivision' as Sedgwick (1852b, p. 137) called the unit. The 'Otley III' rocks are of generally quite low relief, but, as mentioned previously, many are highly cleaved, the cleavage frequently being more pronounced than the bedding. As we have seen, some of the beds are highly fossiliferous (or were so before they became the subject of close attention by generations of amateur and professional geologists, dealers, or even historians of geology). There is (or once was) a rich fauna of graptolites, molluscs, corals, cystoids and trilobites, and in the past more exotic types like starfish were reported by Sedgwick.
As we have seen, the lowest part of 'Otley III' was formerly called the Coniston Limestone (Series) and was initially likened (by Sedgwick) to the Bala Limestone in Wales. Later it was placed in the Caradoc subdivision of the Ordovician; and still later it was subdivided and the
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