2S0 Profess orHailstone on the Geology of Cambridgeshire. 



gault. This occurrence of green sand In the confines of the two 

 beds was' first noticed by Mr. Warburton at the brick pits near the 

 Castle hill, from which he inferred that it always takes place under 

 the same circumstances : an inference which is borne out by the 

 testimony of the most experienced brickmakers about Cambridge. 



I am at a loss where to class the bed of sand and sandstone 

 which lies over the gault at Ely, and forms in some measure the 

 elevation on which that city stands. It contains particles of green 

 sand, but not in suificient quantity to be characteristic. It is 

 principally a concrete of siliceous sand, with small rounded frag- 

 ments of ironstone and quartz pebbles : the bed is from eight to 

 twelve feet in thickness, and perhaps an alluvial deposit. 



It is unnecessary to trouble the Society with an enumeration of 

 all the organic remains that are to be found in the clunch or chalk 

 beds, they are in general the same as occur in other parts of the 

 kingdom where the chalk formation presents itself. Of the 

 remains of fish we find their teeth, bony palates, and in many 

 -cases their brown scales not much altered. Cornua ammonis occur 

 and some bivalves apparently of the chama and mytilus genera. 

 Of the former genus I have found the haliotidea very distinct. 

 The anomia terebratula occurs in the beds at Reach. In the 

 vegetable kingdom the fruit cones of Cherry Hinton deserve a 

 particular notice. As early as Woodward's time this fossil had 

 attracted the attention of naturalists, and two very perfect speci- 

 mens in his collection appear to put their vegetable origin beyond 

 doubt. In confirmation of this opinion, I beg to refer to a fossil 

 In the collection which I have the honor to transmit, which I met 

 with at the same pit, and seems to be the impression of a branch 

 of some vegetable of the fir tribe, with the linear leaves surround- 

 ing it. 



