490 ME. F. W. HABMER ON THE [Nov. I907, 



below Newark is taken from the Geological-Survey map. There are 

 quartzite-gravels in this region which occur at higher levels, being 

 regarded by the officers of the Geological Survey as of Glacial age. 

 Some of the latter, as at Gelston for example, seem to connect 

 themselves, however, with one or other of the gorges ; they may all 

 represent, I think, different stages in the Pleistocene Epoch, later 

 than the Boulder-Clay. 



VII. The Chalky Boulder-Clay of Lincolnshire and 

 the Midlands. 



I take advantage of the publication of the map (PI. XXXIII) 

 to show the distribution of the Glacial deposits in the region in 

 question, so far as material otherwise available and my own 

 observations permit, as well as to sketch out very briefly what, 

 in my opinion, may have been the movements of the ice-streams to 

 which they were due. It is not possible to»give in the present 

 paper the evidence upon which my conclusions are based, but 

 I hope to do so hereafter. 



The enormous area, many thousand square miles in extent, over 

 which the Chalky Boulder-Clay may be traced x shows, I think, 

 that it could not have been wholly originated by ice crossing the 

 Wolds from the North Sea, but that it must also have been due, as 

 before stated, to a glacier descending from the Vale of York. 2 

 The connexion of this deposit with the Lincolnshire Wolds is 

 shown, however, by the fact that it contains everywhere, in almost 

 incredible profusion, blocks of the hard chalk and tabular grey 

 flint characteristic of the Turonian strata of that region. 3 



A study of the contours of the Chalk-escarpment may indicate 

 the points at which the ice moved across the Wolds from the sea. 4 

 Immediately to the north of Market Rasen, the face of the escarp- 

 ment shows no sign of Glacial disturbance, the contour-lines from 

 200 to 500 feet being continuous and closely crowded together. 

 South of that place, on the other hand, the Wolds are intersected 

 by a transverse depression, running north and south, while farther 

 south still the surface of the Chalk is irregular and much broken 

 up, and the hills do not attain the elevation of those on the north. 

 It is in the region lying south of Market Rasen, near Horncastle 



1 See, as to this, S. V. Wood's map in Quart. Journ. Geol. Soc. vol. xxxvi 

 (1880) pi. xxi, republished in Proc. Geol. Assoc, vol. xvii (1902) p. 463. 



2 It was from this direction, I believe, that the Carboniferous detritus 

 frequently met with in the Chalky Boulder-Clay of East Anglia was mainly 

 derived. 



3 Some of the palaeolithic implements found in the Drift-covered area have 

 apparently been chipped out of grey Lincolnshire flint from the Boulder-Clay. 



4 I regret that the views here adopted as to the glaciation of this region 

 differ from those of my friend, Mr. Jukes-Browne ; as to the latter, see his 

 various Survey Memoirs on the geology of Lincolnshire. 



