73 



The more recent changes of the channel certainly seem to 

 have been in this direction, and the present river, which keeps 

 nearly parallel to the low terrace of gravel stretching away 

 from Chesterton through Milton to Waterbeach, begins to take 

 a more easterly course near the latter place, and has left a strip 

 of Gault-land between the gravels and the alluvium. 



I think therefore the westernmost deposits of loam and 

 gravel may safely be taken as the oldest, and those nearer the 

 present river as successively newer ; it is possible also to group 

 them in three series, which may be the continuations of the 

 three terraces described as existing in the higher portion of the 

 valley. Thus the gravel which occupies the ground north of 

 Cambridge towards Impington and Histon may be a continua- 

 tion of the Barnwell series ; patches of loam occur in it here and 

 there, but the.^e ai-e not exposed in any pits where a search for 

 shells might be made. About Impington the Gault comes to 

 the surface in many places, and the gravel only occurs in hollows 

 and channels, but north of Histon there is a large patch forming 

 a low plateau which is cut off abruptly along its northern edge; 

 from this a Gault slope leads down to the valley of a little 

 brook or ditch draining into the Ouse. 



Gravel is also seen along the Roman road between Kino-'s 

 Hedges and Landbeach; indeed the whole country hereabouts 

 seems to have been once covered with gravel, though little more 

 than a gravelly soil now remains to indicate its former 

 presence. 



The Chesterton gravel is at a lower level, and forms part of 

 the terrace above mentioned as stretching for some distance to the 

 N.N.E. in a direction nearly parallel to that of the present 

 river; beyond Milton however it bears nearly due north, and 

 passes between Landbeach and Waterbeach towards Goose 

 Farm and Denny Abbey, disappearing finally under the peaty 

 soil of Cottenham Common and Chaff Fen. 



There are numerous small gravel pits scattered along this 

 strip of country, but they do not show any good sections, and I 

 did not succeed in finding any organic remains. Prof. Seeley 

 says^ that he has found shells at Chesterton and other places, 

 "but in every case they were land or freshwater forms, though 



1 Quart. Journ. Geol. Soc. xxii. p. 475. 



