There are six named ironstone seams which are, in order of deposition, the " Osmotherley, Avicula, Raisdale, Two-foot, Pecten " and " Main"
2.
The lowest 19 metres are predominantly shaley and include the Osmotherly, " Avicula ", Raisdale and Two-foot Seams, the best-developed being the " Avicula"
3.
The lowest 19 metres are predominantly shaley and include the Osmotherly, " Avicula ", Raisdale and Two-foot Seams, the best-developed being the " Avicula"
4.
Fossils are ubiquitous, especially within the ironstone seams, to the extent that the " Avicula " and " Pecten " seams are named after their most abundant faunal inclusions.
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