31 



this portion of the section is now rendered obscure by the over- 

 growth of vegetation. 



From the hills north of Saffron Walden the irregular boun- 

 dary of the Upper Boulder Clay is traceable through Great 

 Chesterford Common and Park, round by Abington Park and 

 Hildersham Wood to Hadstock ; it then runs down northward 

 and skirts the S.W. side of the valley by Linton and Bartlow. 

 This valley here divides into two branches, and the tributary 

 brooks occupying these have cut back the Boulder Clay as far 

 as Ashdon Street and Castle Camps respectively; from this 

 point the boundary turns finally northward, and may be followed 

 over the country a little west of Shudy Camps and Horseheath. 



Throughout all this country the Boulder Clay almost always 

 rests directly upon the Chalk, and it is only in one or two 

 localities that any intermediate gravels have been found. One 

 of these is near Littlebury, where the road-cutting just above 

 the words North End on the Ordnance Map appears to show an 

 upper and a lower clay with an intercalated patch of gravel. 



No more such gi-avel is seen till we reach the slopes above 

 Linton, where it appears to underlie the Boulder Clay rather 

 more extensively, and may be seen in several pits about 

 Hadstock. In the railway-cutting near Newnham Hall Mr W. H. 

 Penning informs me that a lenticular patch of gravel and loam 

 occurs in the mass of the Boulder Clay, near a knob of Chalk 

 which rises up from beneath. (See Geological Survey Memoir 

 on Sheet 47.) At Ashdon a small pit near the Church exhibits 

 a few feet of rough chalky gxavel, but its relation to the Boulder 

 Clay is not seen. 



§ h. Eastern District. Eastward of Ashdon the Boulder 

 Clay appears to stretch uninterruptedly through Castle Camps 

 and Shudy Camps to HeKon Bumpstead and the neighbourhood 

 of Haverhill. This high ground forms the watershed between the 

 valley systems of the Cam on the one hand and the Stour on the 

 other; hence the small brooks and streams which form the 

 tributaries of these two rivers run off the Boulder Clay slopes 

 northward, eastward and westward. The lower formations are 

 entirely veiled by the clay, nor is anything else seen till the 

 vicinity of Haverhill is reached ; Avhere several sections show 

 gravelly beds miderlying the clay. One of these occurs about 



