Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/258

 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 sufficient quantity to be characteristic. It is principally a concrete of siliceous sand, with small rounded fragments 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 ammonia 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 specimens 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 surrounding it.