394 Glacial Epoch. 



thus presenting points of resemblance to the sections 

 on the coast which I have described between Berwick- 

 on-Tweed and the mouth of the Humber. These sands 

 and gravels which contain sea-shells have been named 

 by these gentlemen ' Middle Glacial.' 



The Upper Grlacial Boulder-clay has been called by 

 Mr. Wood and Mr. Skertchly the great Chalky Boulder- 

 clay, from the circumstance that it chiefly consists of 

 chalk, ground up by an advancing glacier travelling 

 frcm north-east to south-west, the chalky and flinty 

 debris being sparingly mingled with fragments of 

 Oolite, quartz, basalt, granite, &c., sometimes smooth 

 and striated. Though chiefly formed of chalky material, 

 yet when found lying on Kimeridge Clay it is found to 

 be mingled with the detritus of that formation, and 

 when it reaches the Oxford Clay, all three are inter- 

 mingled. The Boulder-clay lying on each formation 

 that lay under the glacier ice-sheet, which was invading 

 the country from north to south, always partakes of 

 the nature of the underlying rock, and the total area 

 occupied by this chalky Boulder-clay must, according 

 to Mr. Skertchly, have been more than 3,000 square 

 miles in the south-east of England. If, however, this 

 supposed glacier extended as far south as Romford, 

 where there is Boulder-clay with scratched chalk-flints 

 and masses of Oxford and Kimeridge Clay, then the 

 area covered by the great Chalky Boulder-clay and its 

 southern continuation instead of 3,000 square miles 

 must have covered 9,000 or 10,000 square miles of 

 ground. 



It must now be evident to the reader, that on the 

 east coast of England, and on the adjoining ground in 

 the interior, there is no want of evidence of a cold 

 episode or of episodes when snow and glacier-ice largely 



