( Read, September, 1945). I. Introduction. The area under consideration forms the northern edge of the Carboniferous limestone plateau described by Shirley and Horsfield in 1940, and includes the narrow gorges of the Winnats, Cave Dale and Pin Dale. The lower ground to the west, north and northeast is occupied by Edale Shales which were shown to be unconformable to the limestone in 1925 by Jackson. Subsequent papers by the same author have made substantial additions to our knowledge of these richly fossiliferous limestones. Jackson’s views of the succession given in his latest paper (1941b) differ fundamentally from those of Shirley and Horsfield. Preliminary work in the area by the author (1943) led to conclusions broadly in agreement with those of Jackson. Two recent papers by Hudson and Cotton (1945a and b) have described in detail the strata of Middle and Upper Visean age encountered in the Alport and Edale borings north of the limestone massif. Hudson and Cotton correlate the beds in these bores with those of Castleton and elsewhere and adduce considerable evidence against Shirley’s and Horsfield’s view that the Castleton reef limestones rest with strong unconformity on strata of D1D2 age. During the present investigation many fossils have been collected, but with a few exceptions, only those forms having some zonal value have been recorded in the following pages. Fully representative faunas from all the localities examined would take a long time to collect and identify. On several occasions during the last few years the author has been ...