274 Mr. S . V. Wood on the Events which produced and terminated 



rations arrived, of the extension of this palaeozoic barrier from 

 the Warwickshire coal-field in an E.S.E. direction, appears to me 

 therefore to obtain some confirmation from the interruptions in, 

 or departure from, the normal direction of the anticlinal and syn- 

 clinal lines produced by the Weald upheaval. If these conjec- 

 tures have any sufficient foundation, the configuration of the 

 east of England would, if the cretaceous and tertiary covering 

 were removed, show very similar features to the west, where the 

 palaeozoic area curves northwards along the valley of the Severn 

 — both the eastern and western palaeozoic areas being separated 

 from the Penine chain by straits, the severance of the two areas 

 having been caused by the upheaval of that chain*. If the direc- 

 tion of this ancient barrier be correctly inferred, we have the 

 following succession of geographical configuration over the south- 

 east of England and north-west of France. 



During the mesozoic period, up to the newer cretaceous epoch, 

 a basin existed, bounded on the north-east by this barrier, on 

 the north by the southern extremity of the Penine chain, on the 

 north-west by the Silurian system of Wales and Shropshire, on 

 the west and south-west by the carboniferous systems of South 

 Wales and North Devon and the ancient rocks of Brittany, and 

 to the south-east by the crystalline plateau of Central Prance. 

 At the earlier part of this period, when the stage of greatest 

 depression in most parts of it occurred, viz. during the Triassic 

 age, the basin existed in the form of a strait connecting the 

 Triassic sea of Germany with the Triassic waters of the north of 

 Ireland on the one side, and those of the north-east of England 

 on the other. At the commencement of the Jurassic age, how- 

 ever, when great changes of level had taken place, converting- 

 great parts of the Triassic sea of Germany into land, the Anglo- 

 Prankish basin had become considerably modified. At this epoch 

 the basin had four openings : one in Cheshire, forming the 

 north-western opening and probably extending in a narrow 



* The tract of which these palaeozoic areas once formed part, appeal's to 

 have been one of those axes to which I have elsewhere (Phil. Mag. 1862, 

 vol. xxiii. p. 164) adverted as having come into existence during the carboni- 

 ferous age in various parts of the world, with a direction generally east and 

 west, marking the direction of the lines of volcanic action during that period. 

 This axis, although now exposed only in fragments, appears to have been 

 originally of great extent — the portion which extends from the west of Ire- 

 land to the east of Germany being probably connected on the east with a 

 similar axis said by M. Abich to extend through Southern Russia, and on 

 the west with the axis of Newfoundland. The upheaval of the Penine 

 chain destroyed the continuity of that portion of the axis which crossed the 

 British Isles ; and its consequent and contiguous depressions formed the 

 northern head and north-eastern and north-western openings of a basin 

 that first, with a portion of the north-eastern opening probably as land, 

 received the Permian sea, and afterwards, with that opening at its greatest 

 submergence, the sea of the Trias. 



