69 



Comberton, and it was from this I presume that the tooth of Rh. 

 tichorkiinis mentioned by Mr Seeley was obtained. 



Beyond this point the terrace cannot be traced, and it has 

 probably been carried away by subsequent denudation into the 

 newer gravels below. 



§ b. Returning again to Cambridge as the starting point, 

 the gravel which underlies Downing College, New Town and 

 the Botanical Gardens, and presents an evident bank to the 

 river near Mr Bland's farm, is found to stretch up both sides of 

 Vicar's Brook, and to occupy the shallow valley previously 

 mentioned as cutting through the older (Barnwell) series between 

 Brookland Farm and Trumpington Mill (see also Fig. 7). At 

 the cottage where the Mill Road crosses the railway, there is said 

 to be 12 or 15 feet of gravel, and the same material continues to 

 occupy the low ground as far as Shelford, where it may be seen 

 in pits near the bridge over the Cambridge and Hitchin railway; 

 gravel underlies most of Great Shelford and is from 8 to 12 feet 

 deep in various parts of the village, ending abruptly against the 

 river ; but on the other side of the alluvium it appears to be 

 continued by Frog Hall to Whittlesford. Beyond this it is not 

 easy to separate it from gravels of later date, and the same may 

 be said of its continuation up the Linton Valley by Howe Field, 

 Babraham and Abinoton, for g-ravel is found aloncj the banks of 

 both streams at all levels from the recent alluvium to a height 

 of thirty or forty feet above it. 



It would appear, therefore, that at the period in the history 

 of the Cam valley which we have now reached, these united 

 streams did not take their present course by Little Shelford and 

 Hauxton, but ran nearly due north, as far as Cambridge, before 

 they were joined by the Rhee and Bourn. 



As regards the Rhee, indeed, we have already shown that it 

 could hardly be said to have any existence ; the upjDer part of 

 its course being so very different from that which it now 

 follows, and the main stream at this time being probably that' 

 which descends from Wardington Bottom. 



Gravel occurs on the east side of the Rhee, both north and 

 south of Harston, but at no great height above the river, and 

 these patches seem to lead on to a much larger spread of gravel 



