DRIFT IN THE VALLEY OF THE CAM, ESSEX. 339 



are two breaks in the contmuitj^ of the Glacial and River Drift 

 along the valley, bare Chalk being mapped between Wenden and 

 jSTewport, and again south of Littlebury. Whether further exami- 

 nation, with fresh evidence, may show the Drift to be continuous is 

 a question to be decided. If the Chalk in the parts mentioned be 

 really bare of Drift, then the channel is not continuous, or, at all 

 events, was in parts so shallow as to have been destroyed in the 

 erosion of the present valley. Between Littlebury and Whittlesford 

 Bridge, a narrow channel, filled with Glacial Drift, may occur 

 beneath the River Drift and the Alluvium, and may be proved by 

 future wells ; but we may perhaps have a set of long narrow basins 

 instead of one more even and continuous channel. 



[PosTSCEiPT. — A well-section at "Whittlesford has been given on 

 page 20 of the Geological Survey Memoir, " The Geology of the 

 Country between and south of Bury St. Edmund's and Newmarket" 

 (1886). Specimens, since seen, show that the bed described as 

 blue clay is a hard grey calcareous band, like some of the loams in 

 the borings alluded to above.] 



Discussion. 



Dr. Evans thought the Author's conclusions would generally 

 commend themselves to Fellows. He gave reasons for rejecting the 

 supposition that these particular depressions were due to chemical 

 solution of the Chalk, and believed that, at the time the depressions 

 were formed, the district was more elevated than it is at present. 

 Under such conditions valleys would be rajDidly denuded with an 

 increased rainfall. There was one curious feature, viz. that the old 

 configuration of the country was sufficiently distinct for the existing 

 valleys to follow the same lines as those of an earlier age. This ele- 

 vation of the country to some extent corresponds with that required 

 oy Mr. Prestwich in connexion with the Westleton Beds, and the 

 axis might well have taken the direction Avhich that Author had 

 inferred. 



Mr. Clement Retk had found several of these old valleys in the 

 ^North of p]ngland, but felt some diffidence in comparing an old valley 

 in hard rocks with one in soft rocks. He suggested as a possibility 

 that the Essex depression might not be a river-channel but a lake- 

 basin, and was desirous of knowing whether it corresponded with 

 the general direction of movement of the ice. 



Mr. ToPLEY was inclined to think that the Preglacial-channel 

 explanation was the most likely one. In Northumberland, the 

 Blyth was, in Preglacial times, a tributary of the Wansbeck, and a 

 deep Preglacial valley, which was filled with Glacial drift, occurred 

 between the present valleys. 



Mr. J. Allen Brown asked why such hollows were called Pre- 

 glacial, rather than Glacial. 



Dr. G. J. HiNDE asked whether there were any striated or foreign 

 pebbles to be met with in the lower beds of the Drift in the 

 depression. 



Q. J. G. S. Xo. 182. 2 B 



