Published online by Cambridge University Press: 01 May 2009
Of the three main lithological units on Cuilcagh, namely, Millstone Grit, Yoredale Sandstone, and Yoredale Shale, particular attention is paid to the latter which attains a thickness of 700 feet. Numerous goniatites were collected from the lowermost 450 feet of it and these establish the existence of the P1b, P1c, P2, E1a zones and possibly the E1c zone also. Higher beds are very poorly fossiliferous and their age is uncertain. Brief comparisons are also made with Yoredale Beds in England and in other parts of Ireland.