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describes the Boulder Clay as extending from top to bottom of 

 the pit, and being full of all sorts of rocks; "at one place," he 

 says, "the upper part is devoid of pebbles or boulders, and at the 

 north end there are rough courses of nodules making a kind of 

 curved stratification... The Clay is capped by about 15 ft. of 

 Gravel, in part interstratified with it." 



In 1865 Mr Searles V. Wood, Junr. published a map of the 

 Upper Tertiaries in the Counties of Norfolk, Suffolk, Essex, 

 Middlesex, Hertford and Cambridge, with remarks and sections 

 (privately printed). In this he establishes the divisions of the 

 Upper, Middle and Lower Drift, describing their general posi- 

 tion and the relation of the latter to the underlying crag. He 

 looks upon the Cromer Till as a Marine Drift but considers its 

 inland chalky representative to have resulted from the action of 

 local glaciers ; the Middle Drift he speaks of as a marine though 

 littoral formation, accumulated in channels and straits between 

 islands which he believes to have been submerged at the 

 incidence of the Upper Drift or true Boulder Clay; this, he says, 

 "bears evidence of being the deposit of an open sea burdened 

 with floe-ice, drifting from shores of Cretaceous and Jurassic 

 strata." At p. 13, he remarks upon the position of the Upper 

 Drift near Sandy and Gamlingay and states that it is here 

 bedded round the Lower Cretaceous sand "which rises like an 

 island from its midst." His explanation of this is not very 

 clear, but if I understand him rightly he believes it to have been 

 an island in the sea of the Middle Drift, and that the Boulder' 

 Clay was dropped first round it and then on it as the area sank 

 beneath the waters of the Upper Drift sea; and that subsequent 

 denudation has removed nearly all the Boulder Clay from the 

 top of the sands. The map, of which these remarks are in 

 explanation, purports to show the distribution of the Crags and 

 of the three divisions of the Drift in the counties mentioned ; 

 among the sections are several through parts of Bedford, Cam- 

 bridge and Huntingdon, illustrating the relation of the Boulder 

 Clay to the Middle Drift and Neocomian Sands. 



1866. In a paper on the Warp and Trail\ the Rev. O. Fisher 

 illustrates his views by a section in an old gravelpit, Victoria 

 Road, Cambridge; the succession here seen was as follows: — 

 1 Quart. Journ. Geol. Soc. xxii. p. 561. 



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