Br. Wheelton Hind— The Toredale Series. 167 



was not strong enongli to carry tlie sediments far out to sea." The 

 sliore-line was by no means constant in position, but advanced 

 south and retreated back again according to the varying rates of 

 sedimentation and depression. 



No real break is, therefore, to be found in tracing the variations 

 in the Carboniferous beds of England from south to north, and the 

 great change of chai-acter is certainly due to conditions of deposit. 

 I think, in spite of recent utterances, that the gi-eat mass of the 

 Lake District could never have been covered by the Carboniferous 

 sea, but remained an island or peninsula during that period. 

 I would insist that deposits of sands and shales are essentially 

 the debris of land, and are always shallow-water deposits ; and in 

 the case of Carboniferous sandstones and shales, the presence of 

 plants in too large numbers to be attributed to drifting by wave- 

 power, is conclusive evidence that such was the case. Marine 

 erosion practically only takes place for a short distance beyond 

 low-water mark, and an examination of conglomerates points to 

 the locality whence the fragments were derived. The fragments of 

 Silurian rocks which are found in the Basement Conglomerate bed 

 are nearly all subangular, and have therefore not been rolled much 

 or carried far; but apart from evidence it is a necessary conclusion 

 that encroachment of the sea must have been gradual, and therefore 

 there must have been an advancing or retreating shore for some 

 j:)eriod of time or other after the earth-movements, which threw the 

 ohier rocks at such an angle that the basement beds of the new 

 (Carboniferous) deposit were laid down on the fractured and 

 upturned edges of the older beds. 



In the South Midlands depression and sedimentation seem to have 

 gone on at a fairly uniform rate for a long period of time, interrupted 

 only by conditions which have left their mark in their shaly 

 partings, rarely exceeding more than a few inches in thickness. 

 In the North and nearer the shore-line, sedimentation was often so 

 far in excess of depression that the terrestrial conditions necessary 

 for the growth of the coal flora obtained. But there came a time 

 even in the southern area when the deposit of limestone became less 

 constant, and instead of the massive deposit the beds are tliinner 

 and assume a more fissile character, these being succeeded by 

 shales containing thin limestones, which in turn are covered in 

 by thick beds of black shale, with occasionally beds of fine, hard, 

 gannister-like sandstone, all of which are, however, peculiar to the 

 Derbyshire and South Yorkshire area. These beds, in common with 

 those of Wensleydale, have received the name of Yoredale Beds, but, 

 unlike them, contain no limestones, except a few irregular, thin 

 bands at the extreme base. If lam coi'rect in my contention that the 

 Yoredale Series of Wensleydale are simply the equivalents of the 

 upper beds of the Carboniferous Limestone (and several authors 

 have seemed to acquiesce in this view) and do not overlie it, then the 

 term Yoredale can no longer be retained for the mass of strata 

 which intervenes between the Millstone Grit and the Carboniferous 

 Limestone in South Yorkshire, Derbyshire, and North Staffordshire. 



