85 



(2) That the valley of the Cam above Whittlesford and its 

 tributary valley through Linton are the oldest channels in the 

 district, dating from a time anterior to the formation of the 

 Chalky Boulder Clay, 



(3) That the valleys radiating from the Chalk escarpment 

 had their inception in early post-glacial times, when the drain- 

 age system was entirely different from that of the present 

 rivers. 



(4) That the first determination of the waters towards the 

 present system is marked by the series to which the Barnwell 

 gravels belong ; that the gravel-filled hollow between Shelford 

 and Cambridge marks an intermediate stage ; and lastly that 

 the present valley of the Rhee and Granta is the newest of all, 

 and that its direction is nearly at right angles to the earliest 

 lines of drainage. 



CAMlilllDGE : riiXNTKl; liY C. J. CLAY, II. A., AT TUE UNIVEliSlTY PKESS. 



