TRANSACTIONS OF THE SECTIONS. 75 



case as regarded the absence of coal in the eastern and portions of the midland 

 counties, now overspread by Mesozoic formations. The author proceeded to show 

 that there was evidence that the coal-measures were originally deposited in two 

 continuous sheets, one to the north and the other to the south of a ridge of old 

 land, formed of SUurisn rocks, which stretched eastward from Shropshire, and 

 ranged along the south of the Dudley coal-field. This dividing ridge, or bai-rier, 

 had probably never been altogether submerged beneath the waters in which the 

 coal-measures were deposited. Referring to the tract of coal-measures which lay 

 to the noi-th of the central barrier, it was shown that towards the north the boun- 

 daries of the coal-formation were formed by the Cambro-Silurian rocks of North 

 Wales, the Lake-district, and portions of the " southern uplands " of Scotland. 

 The southern limits were formed by the ban-ier of old land, and over this inter- 

 vening area the coal-measures were spread in one continuous sheet, and attained 

 their greatest vertical dimensions towards the north-west. To the south of the 

 barrier, the strata were deposited in the greatest thickness towards the west or 

 south-west. 



At the close of the coal-period, disturbances of strata (resulting probably from 

 lateral pressure acting from the north and south) took place over the whole Car- 

 boniferous area of the north of England, whereby the strata were thrown into a 

 series of folds, the axes of which ranged along approximately east and west lines. 

 These disturbances were accompanied and followed by enormous denudations, by 

 which the coal-measures were swept away over large tracts of the north of 

 England, and the northern limits of the Lancashii'e and Yorkshire coal-fields were 

 approximately determined. 



Referring to the tract south of the central barrier. Professor Hull expressed his 

 opinion that the east and west flexures, beiag parallel to those of the north of 

 England, were referable to the same geological period, namely, post-Carboniferoua 

 (or pre-Permian). At this period the northern and southern limits of the South 

 Wales coal-field, the axis of the Mendip IliUs, and the easterly trend of the culm- 

 measures of Devonshke were determined. Denudation of strata on an enormous 

 scale accompanied these movements. After the deposition of the Permian beds 

 over the inclined and denuded edges of the Carboniferous rocks, disturbances 

 accompanied by extensive denudation took place along lines nearly at right angles 

 to those of the preceding period ; that is, along north and south lines approxi- 

 mately. To this epoch, the axis of the Pennine chain and all north and south 

 trendings of the strata were to be referred. Some of the results brought about by 

 these movements were the disseverance of the Lancashire and Cheshire from the 

 Yorkshire and Derbyshire coal-fields, the determination of the western limits of 

 the Flintshire and Derbyshire coal-fields, the disseverance of the Forest of Dean 

 coal-field from that of South Wales, and the uptUting of the Lower Carboniferous 

 rocks along the eastern margin of the Somersetshire coal-field, beneath the Jurassic 

 formations. From these considerations it seemed clear to the author that the 

 basin-shaped form of nearly all the coal-fields (the basins being sometimes partially 

 concealed by the Mesozoic rocks) was due to the denudations acting over areas of 

 elevation intersecting each other nearly at right angles, and corresponding to two 

 distinct epochs — the pre-Permian and pre-Triassic. Professor Hull then proceeded 

 to show that over these Carboniferous basins the Permian and Triassic rocks were 

 distributed according to a weU-defined plan of south-easterly attenuation, or thinning 

 away towards the south-east ; and he concluded by discussing the views of Sir R. 

 I. Murchison, Professor Ramsay, and Mr. Godwin-Austen, regarding the existence 

 or absence of coal imder the Cretaceous or Tertiary strata of the south of England. 



On the Bed and Coralline Crags. By Chaeles Jecks. 



The author suggested the following reasons, as rendering it probable that the 

 Red and Coralline are quite as nearly connected with each other as the Red and 

 Norwich Crags. If the palseontological difference between the Red and Norwich 

 Crags be about 20 per cent., and yet be considered synonymous, how is it that the 

 Coralline Crag, which only contains 10 per cent, fewer recent species than the Red, 



