Plateau Gravels 43 



near Linton, to the Gog Magogs, and the many gravel pits 

 which have been opened at intervals along its southern side. 



Similar in many respects to the Plateau Gravels are certain 

 of the * gravels and loams' which occur at intervals along 

 several of the drift-filled valleys of the Chalk escarpment. The 

 material of these is much more thoroughly sorted than that of 

 the Plateau Gravels, but the bedding is highly contorted and 

 is never continuous over any considerable area. Coarse and 

 fine materials alternate in the most capricious manner, and 

 wisps of what seems to be Boulder-clay come iu among them. 

 The loam and many of the finer beds of gravel consist almost 

 entirely of chalk ddbris (including flints), but the pebbly beds 

 and the 'Boulder-clay' contain abundant erratics and especially 

 ganister. No fossils have yet been discovered and altogether 

 the beds are more like fluvioglacial deposits or Boulder-clay 

 made from older gravels than ordinary river gravels. 



The best general exposures are those of the two pits west 

 of Whittlesford station, but the loams are better seen in the 

 railway cuttings south of Chesterford. Similar gravels may 

 also be seen in Wardington Bottom, at the head of the Rhee 

 valley near Roystou, and again high up in the Lin valley about 

 Bartlow station. The much-faulted accumulation of loam and 

 gravel seen in a pit about a third of a mile east of Fordham 

 church seems to belong to these, and with it much of the wide- 

 spreading gravels of the Heath country north of Newmarket 

 may also be included. 



Post-Glacial and Recent. 



The oldest deposits definitely newer than the latest Boulder- 

 clay are the 'gravels of the ancient river system.' These 

 gravels occupy certain now streamless valleys of the chalk 

 escarpment and often cap long ridges which stretch out from 

 the scarp across the low-ground and fen. They differ from 

 the Gravels and Loam series in that they include no wisps of 

 Boulder-clay and are occasionally fossiliferous. Their material 

 includes all constituents of the Boulder-clay and is fairly well 



