GEOLOGY 



cene deposits are distinguished from those of later age by their freedom 

 from cretaceous rock debris. Mr. Deeley divides them into three 

 epochs, viz. the Older Pleistocene, the Middle Pleistocene and the Newer 

 Pleistocene. The Boulder Clays of the lower series, or older epoch, are 

 tough bluish or reddish clays chiefly made up of the subjacent rocks or 

 of those immediately to the north or west and contain fragments of all 

 the Pennine rocks. The boulders in them are such as would be brought 

 down by glaciers descending the valleys of the Derwent and Wye and 

 crossing the valley of the Trent. The clays of the middle and newer 

 epochs contain large quantities of flint and chalk and, except in the west, 

 not so large a proportion of boulders from the Pennine Chain. The 

 beds associated with the Boulder Clays consist of widespread deposits of 

 sand or gravel formed during times of submergence, or of fluviatile gravels 

 occupying terraces bordering the main watercourses. Not only does the 

 development of each deposit vary largely in different localities, but there 

 is an indication of an almost continuous series of changes from early 

 glacial times down to the present day. 



The following is Mr. Deeley's classification of the Pleistocene de- 

 posits in this district : 



NEWER PLEISTOCENE EPOCH 



Later Pennine Boulder Clay. 

 Interglacial River Gravel. 



MIDDLE PLEISTOCENE EPOCH 

 Chalky Gravel. 

 Great Chalky Boulder Clay. 

 Melton Sand. 



OLDER PLEISTOCENE EPOCH 



Middle Pennine Boulder Clay. 



Quartzose Sand. 



Early Pennine Boulder Clay. 



Interbedded with the Boulder Clays of the Older Pleistocene are 

 deposits of fine light yellowish or reddish false bedded sand and gravel. 

 A fine section of this sand occurs at Blackwall near Kirk Ireton. It is 

 about 25 feet thick and consists of coarse sand or grit, derived apparently 

 from the breaking up of the Yoredale Sandstone, which forms the ridge 

 upon which it rests. The sand contains numerous pebbles of quartzite, 

 quartz, sandstone, and is obliquely laminated. It is only slightly con- 

 solidated, and at a short distance looks not unlike Bunter pebble beds. 

 Mr. Deeley considers that the Middle Pennine Boulder Clay was formed 

 in the path of the glaciers which came down the valleys of the Derwent, 

 Wye and Dove and crossed the partly submerged valley of the Trent in 

 the direction of the Charnwood Hills. The presence of erratics at 

 Burton-on-Trent foreign to the district point to the deflection of the 

 Scotch and Cumbrian glaciers into the western portion of the Trent 

 basin. 



Several masses of this Boulder Clay have been found in the southern 

 part of Derbyshire. At the village of Spondon east of Derby is a 



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