610 MR. P. G. H. BOSWELL OK THE [Dec. I913, 



+ 137, and +146 feet O.D. It is also possible that there is a 

 hollow in the Lark Valley near Lackford, but these north-westward 

 flowing rivers connected with the Wash drainage are outside the 

 area discussed in this paper. 



The thicknesses of Drift in all the well-sections in the county have 

 been compared, and all those over 100 feet examined. These 

 latter were found to be on the higher parts of the plateau, where 

 such a thickness would be expected, or in the valleys, where they 

 showed deep channels in older beds. 



The conclusion then arrived at is, that in every valley of any 

 size in Suffolk, a deep channel filled with Drift occurs. In some 

 valleys: for instance, the Brett and the Gipping, two such channels 

 appear to be in alignment (unless the one channel takes a very 

 winding course, which is rendered improbable by the evidence of 

 numerous borings on the sides of the valley). It will be noticed 

 that these channels, together with those recorded in the Cam Valley, 

 in the Een district, the Stort Valley, Hitchin, and Yarmouth, form 

 a roughly radiating series. Those which occur near the sea (Brett, 

 Gipping, Deben) are possibly separated from it by a sill or 

 threshold ; but, here again, they may take a circuitous course and 

 maintain their depth to the sea, although the evidence is not at all 

 satisfactory. At Ipswich, where we have a large number of 

 borings, both in the town and in the surrounding country, it is 

 difficult to understand why such a sill should not exist (see fig. 4, 

 p. 602). More borings are needed to outline the form of the channels 

 accurately; but, from those that have been put down, particularly 

 on the sides of the valleys, the channels are seen to be of long 

 narrow form, and in the area discussed all lie in a Driftr covered, 

 receutly-glaciated plain stretching to the sea. The data are not 

 sufficient to enable us to draw with certainty the longitudinal 

 profiles of these channels. There is good evidence in the district 

 for believing that the county stood at a higher level in Glacial 

 times ; but the evidence is rather against the view that the now- 

 buried channels were carved out by ordinary river-action. There- 

 is no uniformity in the depth to which they are cut, as the following 

 comparison shows : — 



Channel. Depth in feet recorded, below O.D. 



Glemsford -347 



Brett enham — 32 



Hadleigh - 40 



Stowmarket — 5 



Ipswich —117 



Woodbridge —176 



River Aide — 3 



Hoxne - 40 



Euston -140 



Moreover, the finding of the rounded flints, unstained and 

 unaltered, at the base of the Ipswich channel, points to pot- 

 hole action, but not that of an ordinary open torrent. We do 



