SUCCESSION IN THE TRENT BASIN. 455 



and flint, immediately above and below, or even interstratified with, 

 the Great Chalk)?- Boulder-clay, points to the conclusion that the ice- 

 sheet of this stage did not enter a district already occupied by Pen- 

 nine ice, but, on the contrary, entered what was then comparatively 

 open water in the Trent basin. The difficulty therefore is, not how 

 the north-easterly ice advanced into this neighbourhood, but rather 

 how* we are to account for the absence of glaciers flowing from the 

 Pennine Chain. Prom these considerations it appears most probable 

 that the Pennine Chain was much lower during the Middle Pleisto- 

 cene epoch than it was when the older Pleistocene Boulder-clays 

 were formed, and that the Great Chalky Boulder-clay advanced into 

 the partially submerged area of the Trent basin. 



The Great Chalky Boulder-clay is generally a true ground-moraine, 

 but in some places, such as Chellaston, Melton Mowbray, Market 

 Bosworth, Abbots Bromley, &c., it presents indubitable signs of 

 aqueous action. 



"When the glacier of this epoch melted away, the country was left 

 submerged to a considerable depth beneath the ocean. Gravels 

 were then formed upon the Chalky Clay and other exposed rocks, 

 especially upon the southern and western watershed of the Trent 

 basin, where the Atlantic beat upon the islands, and surged through 

 the straits or over the shoals. The same phenomena exist in the 

 central portions of the Trent basin, but, probably owing to the land- 

 locked nature of the area, they do not reach such a great develop- 

 ment. These gravelly deposits, which I have called the Chalky 

 Gravel, contain a great variety of rock-fragments derived from the 

 Chalky Clay or adjacent rocks. In many instances chalk, both as 

 pebbles and sand, forms no inconsiderable percentage of the deposit. 



1. Melton Sand, 



The Melton Sand occurs very sparingly between the older rocks 

 and the Great Chalky Boulder-clay. The deposits of this stage 

 ^ dealt with were formed within the watershed of the Trent in a sea 

 of tolerable extent and depth, probably connected with the ocean by 

 straits to the westward. The land-locked, and probably ice-locked, 

 nature of the Melton-Sand sea did not favour the formation of 

 much clean false-bedded sand. The Melton Sand consists chiefly of 

 stratified sand, with occasional beds of gravel or loam. A stray flint 

 may be sometimes found in some of the older Pleistocene gravels or 

 Boulder-clays, but in the Melton Sand they suddenly make their 

 appearance in great numbers for the first time. 



Unfortunately no section has yet been found showing the passage 

 of Older Pleistocene Boulder-clay into Middle Pleistocene sand. 

 Indeed there appears to have been somewhat of a break between 

 these two epochs, perhaps partly due to temporary elevation and 

 subaerial denudation. This break, which partakes of the nature of 

 an unconformity, is clearly shown in many sections. 



At Leicester Abbey the brown Middle Pennine Boulder-clay is 

 separated by a marked line of division from the Chalky Clay above. 



2i2 



