190 NEOZOIC TIME. [CHAP. X. 



the basin of the Irish Sea. If the prevalent current set 

 from the south-west, this curve of the shore would tend to 

 give it an easterly course, so that it may have passed sea- 

 ward and eastward from over the north of Warwick, which 

 will account for the great eastward extension of the G-ault, 

 and also for its absence north of latitude 52 50 7 . 



The geography above suggested and represented in the 

 map, Plate IX., assumes that the Pennine hills were not 

 submerged, and, as this is an important point, we may 

 consider it a little more closely. We know that the relations 

 of the Jurassic and Cretaceous strata in the north-east of 

 England are similar to those of their south-western equi- 

 valents ; it is clear that the Upper Cretaceous sea, aided by 

 subsidence, marched across the Jurassic ground and formed 

 a plane of erosion that sloped gradually up to the Palaeozoic 

 hills. Now at Grarraby, which is nearly the most westerly 

 point of the Yorkshire Wolds, the Red Chalk, or horno- 

 taxial equivalent of the G-ault, rests directly on the Lias at 

 an elevation of about 600 feet ; a few miles further west 

 it must have lain on the Trias, and thence the sea-floor 

 probably passed with a gentle slope to the foot of the 

 Pennine hills. How far the Red Chalk extended in a 

 westerly direction we cannot say, but sooner or later it 

 probably passed into a more littoral deposit ; comparatively 

 deep water (100 to 150 fathoms) may, however, have 

 continued to within a short distance of the shore-line, and 

 the Pennine hills probably rose up from the sea with a 

 steep slope, as the Riviera does from the G-ulf of Grenoa. 

 Thus, if the base of the Chalk reached to what would now 

 be a level of 900 feet over the edge of the Trias sic boun- 

 dary, and we suppose the water there to have been 600 

 feet deep, it would not have overtopped the Pennine hills, 

 which even now rise in many places to heights of over 

 2,000 feet, and in the Cretaceous period the watershed 

 must have been much higher than it is now. Hence I do 



