A HISTORY OF DERBYSHIRE 



denoted by the trend of the furrows and ridges of the contortions. 

 There have been several good exposures of these gravels in and near 

 Derby. 



THE UPLANDS 



It has generally been considered that the uplands of Derbyshire are 

 comparatively free from glacial drift. This is because the subject has 

 received very little consideration at the hands of geologists. The litera- 

 ture is very meagre and is mainly confined to the Geological Survey 

 memoir which has often been quoted in favour of the absence of drift on 

 the tableland and of the transport of erratics in the valley of the Wye 

 to floating ice rather than to land ice. From what is apparently merely 

 negative evidence it has been inferred that the tableland has never been 

 overflowed by ice. Mr. Deeley considered that the Pennine debris was 

 brought by glaciers flowing down the valleys of the Dove, the Wye and 

 the Derwent, but geologists have carefully reserved judgment until some- 

 thing like moraines or evidences of glaciers are found in the valleys. 

 The Bloody Stone near Cromford has been quoted as a doubtful case of a 

 glaciated rock floor. This stone is composed of a quartzose or silicious 

 limestone, and it is more likely that the groovings are either slickenside 

 or part of the rock structure than that they are due to glacial action. 

 But we are no longer dependent on the Bloody Stone as a doubtful wit- 

 ness to the glaciation of the uplands. The presence of a large mass of 

 Boulder Clay near the village of Crich has long been known. About 

 two years ago Mr. Deeley and the writer found that the limestone floor, 

 which had been recently exposed by removal of the Boulder Clay, 

 was finely striated, polished and grooved. The striae ran north 20 

 west, indicating an ice flow roughly coinciding in direction with the 

 neighbouring Derwent valley. Large masses of drift cover the ground 

 in the neighbourhood of Ashbourne and Tissington. On Spital Hill 

 south of Ashbourne 50 feet of Boulder Clay were sunk through before 

 reaching the Keuper Marl, and the most of the cuttings in the new 

 railway between Ashbourne and Tissington were in Boulder Clay. Near 

 Bakewell, Stanton, Youlgreave and on the dip slope of Riber Hill near 

 Matlock traces of Boulder Clay containing striated blocks of Mountain 

 Limestone, Gritstone, Toadstone, and in a few cases foreign erratics were 

 noticed by the Geological Survey. They considered that the drift came 

 from the west along a gap cutting across the great barrier of the Pennine 

 Chain ; that its path was up the Goyt valley by Doveholes and Buxton 

 and thence down the valley of the Wye ; that a depression or sub- 

 mergence of 1,100 to 1,200 feet converted this pass into a strait and 

 that the foreign erratics found in the drift of the Wye valley were car- 

 ried from the west on floating ice. The occurrence of high level 

 gravels containing marine shells at Macclesfield, Moeltryfaen and other 

 places has been quoted as evidence of a submergence of at least 1,000 feet. 

 On the other hand it is contended with a great deal of reason that the 

 glaciation in north Derbyshire is due to land ice rather than to floating 



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