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

For many years the rising-up of older rocks beneath the Cretaceous beds of the London Basin, and beneath the Jurassic rocks to the north and to the west, has been brought in evidence before us by means of deep wells and borings. It may therefore be a welcome change to notice an occurrence of an opposite kind, the evidence of which is, in like manner, almost wholly owing to the well-sinker. In Scotland long and deep channels, filled with Drift, have been noticed, and have been referred to river-action * . In the northern part of England, too, the like has been observed † ; but I am not aware of the occurrence of such channels in Southern England, except on a small scale, having been described. It is perhaps well, therefore, to bring before the Society evidence that shows a sudden and deep extension downward of beds of late geologic age, namely the Glacial Drift, which are usually of no very great thickness, and which, in the tract in question, occur chiefly on the higher grounds. In the Geological Survey Memoir that treats of the part of Essex that borders on Hertfordshire and Cambridgeshire, there is an account of a well-section at Wenden, showing an unexampled thickness of Drift at a comparatively low level, and also a description of two railway-sections that show the Drift abruptly abutting against the Chalk. In the Geological Survey Memoir that treats of the part of Essex that borders on Hertfordshire and Cambridgeshire, there is an