478 ME. R. M. DEELET ON THE PLEISTOCENE 



slopes of Mill Hill, and also over the interglacial alluvium on the 

 south-west side of Derby. Many good exposures have been opened 

 out in excavating for cellars. On the Normanton road, at the top 

 of Hartington Street, a very good section was shown. About 9 feet 

 of Boulder-clay, consisting of red marl, with sand, large flints, and 

 pebbles, rested upon a violently contorted bed of sand in the Keuper. 

 The Boulder-clay had evidently been thrust over the sand by a force 

 acting from the west and north. 



Cortorted sandy Boulder-clay, with great numbers of flints and 

 occasional large boulders of Carboniferous Limestone, gritstone, &c., 

 caps the western escarpment of the Derwent where it overlooks 

 Little Chester. 



Along the north side of the Derwent, from Borrowash to Long 

 Eaton, the same gravelly Boulder-clay is extensively spread out. 

 In addition to several sections at Borrowash and Draycott, a 

 good exposure may be seen in a brick-yard near Wilsthorp Cottage, 

 south-east of Risley. 



In the Erewash valley, at Stanton Gate, the Later Pennine 

 Boulder-clay, which is exposed in a brick-yard, has been formed by 

 the breaking up of the clays of the Coal-measure period. Similar 

 Boulder-clay was shown in an excavation on the road leading from 

 the station to Ilkeston. At this spot a thin seam of coal had been 

 trailed in a direction, as near as could be made out, down the valley. 



In the Leen valley, near Nottingham, the Boulder-clay, according 

 to Mr. Shipman, reaches a thickness varying from 2 to 6 feet. The 

 deposit was well exposed in sinking wells for new gasholders. At 

 E-adford the modern alluvium of the Leen occupies a wide trench cut 

 through the Boulder-clay. Here it is a stiff sandy clay thickly 

 studded with pebbles ; no regular bedding is visible, the pebbles 

 lying in the clayey matrix at all angles. 



Speaking of the distribution of the Boiilder-clay, and after referring 

 to the existence of older deposits, Mr. Shipman says*, " It was during 

 the last of these periods of glaciation that the red loamy and pebbly 

 sand seen along the foot of the south wall of Wollaton Park, and, 

 indeed, the whole of the drift of the parish of Lenton, appears to 

 have been deposited. It bears evidence of having been derived from 

 the grinding down of the rocks by the passage of ice as it descended 

 from the Pennine Hills across the country in a south-easterly 

 direction ; for the chief ingredients of the deposit are invariably such 

 as could only have come from the north or north-west, mixed up 

 with materials derived from the grinding down of the rocks on which 

 the deposits rest. Pour or five miles further west, in the neighbour- 

 hood of Stanton Gate, beyond the Erewash, drift-deposits of this age 

 assume considerable importance, and betray all the usual signs of 

 ice-action, such as highly disturbed bedding, in which strata have 

 been crumpled and puckered and the pebbles squeezed into a highly 

 inclined or vertical position by the action of lateral pressure ; while 

 in other spots the drift consists of a heterogeneous mixture of 



* ' Geology of the Parish of Lenton.' 



