448 



ME. E. M. DEELET ON THE PLEISTOCENE 



crammed full of Primary rock from the Pennine axis. I have 

 therefore called it the Middle Pennine Boulder- clay. 



So far as my observations go, the mass of this clay was formed in 

 the path of the great glaciers which came down the valleys of the 

 Derwent, Wye, and Dove, and crossed the partially submerged 

 valley of the Trent in the direction of the Charnwood Hills. In 

 addition to the ice-3tream which came down the northern and 

 western tributaries of the Trent, the press of ice in the Irish Sea 

 seems to have led to the deflection of the Scotch and Cumbrian 

 glaciers into the western portion of the Trent basin ; for at Burton- 

 on-Trent there are in the Pennine Boulder-clay erratics entirely 

 foreign to this area. 



In dealing with these deposits it must not be forgotten that the 

 advent of such great ice-sheets has so disturbed the floors over which 

 they passed that in some cases almost alt traces of arrangement in 

 the earlier sands and clays, or at least the possibility of deciphering 

 them, have been destroyed. I shall therefore be compelled, as I 

 mentioned before, to regard some of what are probably rearranged 

 earlier deposits as belonging to the present stage. 



The only section I have seen of Older Pleistocene Boulder-clay 

 containing erratics, probably of Cambrian origin, occurs on Waterloo 

 Hill, near Burton-on-Trent, There is some diffi.culty in examining 

 the clay, owing to its position in the section; but its mode of 

 occurrence, colour, &c. all point to an early ice-flow from the north- 

 west. 



The village of Spondon, to the east of Derby, is built on the south- 

 west side of a considerable mass of Boulder-clay, shown on the map 

 (fig. 1). The deposit is now only to be seen in section at three 

 points — one in the small ravine excavated by the brook which comes 

 down from Borrowood ; another in the road leading to Spondon from 

 the Nottingham road, just beyond the fourth milestone from Derby ; 

 and another in Mr. Coxon's brick-yard in the village itself (this 

 brick-yard lies to the north of the Swan Inn). A total thickness of 

 9 feet is shown. The upper 5 or 6 feet is a light brownish or drab 

 stiff clay, with no signs of bedding, and stuck full of pebbles and 

 boulders of all shapes and sizes. This upper portion contains a few 

 flints and seems to be a disturbed and weathered variety of the main 

 mass of pale bluish or brownish Boulder-clay which lies below. A 

 well sunk in the brick-yard proved the Boulder-clay to be at least 

 60 feet thick. It maintains the same physical characteristics 

 throughout, and rests upon a contorted surface of Keuper marl and 

 skerry. The clayey matrix, composed chiefly of Coal-measure clay 

 with varying proportions of Keuper marl, is wholly unstratified, and 

 weathers bluish along the joint-lines. The pebbles are chiefly 

 nodules of ironstone, mostly broken up. Millstone-grit, black and 

 white chert with Carboniferous-limestone fossils, Coal- measure 

 sandstone, white and black limestone, and coal. The residue con- 

 sists of brown quartzites, white quartz-pebbles, haematite iron-ore, 

 and various other rocks from the Carboniferous formation. Some 

 of the larger erratics, one of which weighed at least six tons, are 



