42 



Similar material is seen in the old railway cutting to the 

 S.S.E., where numerous boulders, many of which are of large 

 size, lie scattered about ; this may however be formed from the 

 loamy and gravelly base of the Boulder Clay, as seen near 

 Babraham. The higher ground of Signal Hill is capped with 

 gravelly soil, but no exposure is visible. 



The gravel pits near Worsted Lodge are dug in another 

 outlier forming an elongated patch and lying at much the same 

 level as that on Signal Hill ; the Gravel here is very chalky, 

 consisting at one part entirely of chalk stones, stained yellowish 

 and packed close together. Another small recent excavation in 

 the pit showed the following succession : 



Irregularly bedded sand and fine gravel 3 feet. 



Very chalky gravel 3 „ 



Clean grey saud (bottom not seen) 1 foot. 



Gravel has also been obtained from a small hole farther east, 

 where it contained more flints. Passing across the chalk combe 

 in which Fulbourn Valley Farm is situated and climbing the 

 hill towards Fulbourn Lodge we again find gravel at a similar 

 level, apparently occupying a hollow on the northern side of the 

 hill summit ; it may be seen in the old chalk- and gravel-pits at 

 the western end, where 6 or 7 feet of brown sand and chalky 

 gravel are visible passing southwards into 2 or 3 feet of mere 

 sandy clay and chalk rubble overlying the bedded chalk. 



Copley Hill again is capped by gravel, as are also the Gog- 

 Magog Mills north of Wandlebury, but no sections were exposed 

 at the time of my visit, although the hollows of several old pits 

 were visible. 



The gravel pits which have been noticed by so many writers 

 on Cambridge Geology (see pp. 15, 28, 86, 37) are to be found on 

 the north side of the Old Roman way called Worsted Street, 

 which appears to have been made hereabouts with the gravel 

 obtained from the above-mentioned pits and holes. These are 

 seldom dug now, and though I visited this locality many times 

 between 1872 and 1875, I could only confirm the observations 

 of previous describers as far as the meagre section then exposed 

 allowed of; this was at the east end of the pit and exhibited 

 stiff yellowish sandy clay showing slight lamination and contain- 



