Geological Society of London. 185 



IIL— March 12, 1890.— J. W. Hulke, Esq., F.R.S., Vice-President, 

 in the Chair. — The following communications were read : — 



1. " On a Deep Channel of Drift in the Valley of the Cam, 

 Essex." By W. Whitaker, Esq., B.A., F.E.S., F.G.S. 



In Scotland and in Northern England long and deep channels 

 filled with Drift have been noticed, but not in Southern England. 



For some years one deep well-section has been known which 

 showed a most unexpected thickness of Glacial Drift in the higher 

 part of the valley of the Cam, where that Drift occurs mostly on the 

 higher grounds and is of no very great thickness. Lately, further 

 evidence has come to hand, showing that the occurrence in question 

 is not confined to one spot, but extends for some miles. The beds 

 found are for the most part loamy or clayey. 



At the head of the valley various wells at Quendon and Rickling 

 show irregularities in the thickness of the Drift, the Chalk coming 

 to or near the surface in some places, whilst it is nearly 100 feet 

 below it sometimes. 



Further north, at Newport, we have the greatest thickness of 

 Drift hitherto recorded in the South of England, and then without 

 reaching the base. At one spot a well reached Chalk at 75 feet ; 

 whilst about 150 feet off that rock crops out, showing a slope of the 

 Chalk-surface of 1 in 2. In the most interesting of all the wells, 

 after boring to the depth of 840 feet, the work was abandoned 

 without reaching the Chalk, the Drift in this case reaching to a 

 depth of about 140 feet below the level of the sea, though the place 

 is far inland. The Chalk crops out about 1000 feet eastward, and 

 at but little lower level, so that there is a fall of about 1 in 3 over a 

 long distance. 



At and near Wenden the abrupt way in which Drift comes on 

 against Chalk has been seen in open sections. Two wells have 

 shown a thickness of 210 and 296 feet of Drift respectively; and as 

 the Chalk comes to the surface, at a level certainly not lower, only 

 140 yards from the latter, the Chalk-surface must have a slope of I 

 in less than 1^, and this surface must rise again on the other side, as 

 the Chalk again crops out. The Drift here reaches to a depth of 60 

 or 70 feet below the sea-level. 



At Littlebury, in the centre of the village, a boring 218 feet deep 

 has not pierced through the Drift, which reaches to 60 feet below 

 the sea-level. As in a well only 60 yards west and slightly higher, 

 the Chalk was touched at 6 feet, there must here be a fall of the 

 Chalk-surface of about 1*2 in 1. Eastward too, on the other side of 

 the valley, the Chalk rises to the surface. 



The places that have been mentioned range over a distance of 6 

 miles. How much further the Drift-channel may go is not known, 

 neither can we say to what steepness the slope of the underground 

 Chalk-surface may reach ; the slopes given in each case are the 

 lowest possible. 



The author thinks that the channel has been formed by erosion 

 rather than by disturbance or dissolution of the Chalk. 



