N^oles arid Comments. 



243 



duction, forms a valuable memento of a memorable event. 

 In addition, the same publishing house has issued the 

 'Order of Proceedings at the Darwin Celebrations/ with 

 a sketch of Darwin's life. It is illustrated by a number 

 •of most interesting photographs, and can be obtained at half- 

 a-crown. 



THE BOULDERS OF THE CAMBRIDGE DRIFT. 



Some interesting notes on the ice-borne erratics of the Cam- 

 bridge drift were recently read to the Geological Society of 

 London, by Messrs. R. H. Rastall and J. Romanes. For 

 several years past large numbers of boulders have been collected 

 from the glacial drifts of Cambridgeshire, and from the post- 

 glacial gravels which have been derived from the drifts. These 

 specimens have been classified geographically and then sub- 

 jected to a careful petrological examination, with a view to the 

 •determination of their origin. Some special collections from 

 Hitchin and Bedford have also been included for comparison. 

 Rocks of Scandinavian origin, and especially those of the 

 Christiania province, are abundant throughout the whole 

 area : such well-known types as rhomb-porphyry and nord- 

 markite are common. Rocks from the Cheviots and Central 

 Scotland are more abundant than was formerly believed, and 

 specimens have also been identified from the old red sand- 

 stone conglomerates of Forfarshire and from Buchan Ness 

 (Aberdeenshire). Lake-District rocks probably also occur in 

 small quantity. Much of the chalk and flints appears to be 

 qf northern origin. 



BOULDER CLAYS. 



It is concluded that an older boulder-clay, containing 

 foreign erratics, the equivalent of the Cromer Till, once 

 extended over the whole district, but was subsequently in- 

 corporated with the great chalky boulder-clay. The 

 Scandinavian ice advanced from the direction of the Wash, 

 bringing with it red chalk and bored Gryphoeas from the bed 

 of the North Sea, and carrying them as far west as Bedford. 

 Rocks from the north of the British Isles become progressively 

 scarcer from west to east, and the distinctive types are absent 

 to the east of Cambridge. They appear to have been brought 

 by an ice-stream coming from a northerly direction, which 

 probably to a certain extent, replaced the Scandinavian ice 

 towards the east. 



1909 July I. 



