374 DISTURBANCES IN THE CHALK NEAR ROYSTON. [Aug. I9O3, 



It did not there cut down to the Chalk or the Eocene beds, except 

 in the valleys. It is worthy of notice that the valleys of East 

 Anglia, speaking generally, radiate from the Fenland region like the 

 divisions of a fan. To a considerable extent they have been ex- 

 cavated, or deepened, in Glacial times, and may represent gigantic 

 striae, and the direction of the ice-flow. He quite agreed with 

 Sedgwick's opinion that combes (and, he thought, gorges also) were 

 due to floods, rather than to slow erosion. In Italy, from which 

 country he had just returned, there has been an extraordinary amount 

 of post- Pliocene denudation. The Italian geologists with whom he 

 had discussed the subject were all strongly of opinion that this 

 denudation could only have taken place under meteorological 

 conditions of* much greater intensity than those of the present time. 

 The evidence for a ' pluvial ' period is very strong in the South of 

 Europe. 



Prof. Groom said that it appeared difficult to explain the 

 remarkable disposition of the Jurassic beds at Shotover Hill, 

 shown to him by Prof. Sollas, on the hypothesis of ordinary tectonic 

 movements ; thrust by moving ice seemed to afford the best 

 explanation. 



The Author remarked that the subject of the mode of glaciation 

 must be dealt with in a large way. As an instance of land- 

 glaciation he referred to a section on the Great Central Railway 

 north of Brackley, where Great Oolite with its rubbly top and 

 brown soil were covered by Boulder-Clay, while farther north 

 the rubble and soil had been swept away, the Great Oolite was 

 directly covered by Boulder-Clay, and in this Drift were streaks of 

 brown soil from the old land-surface. He referred also to the 

 remarkably-even scarp of the Lincolnshire Limestone, and to the 

 absence of outliers in advance of it, as possibly due to glaciation, 

 the results of which were found in the large transported masses of 

 Jurassic limestone, described by John Morris and Prof. Judd, in the 

 area to the south. In his experience the evidences of disturbance 

 beneath the Boulder-Clay were abundant, and he could not in this 

 respect agree with Mr. Hill. 



With regard to the observations of Prof. Sollas and Prof. Groom, 

 he thought that their ' Pleistocene gravel ' might be newer than the 

 Boulder-Clay, but Boulder-Clay did occur, not so very far off, to the 

 north of Bicester and Grendon Underwood. 



In answer to the Bev. J. E. Blake, he remarked that shear-planes 

 in the ice were probably numerous, and it was not difficult to imagine 

 a mass of debris-laden ice being thrust under a disturbed portion of 

 Chalk. In the pit near Newsell's Park the Chalk was much shat- 

 tered, and in the underlying Boulder-Clay he had found Cambridge 

 eoprolites and Lower Greensand, as well as glaciated Chalk. 



