On the Corallian Rocks of St. Ives (Huntingdonshire) and Elsworth

I. Introductory Remarks Lately while mapping the Ampthill Clay, I have been able to trace the Elsworth and St. Ives Rock for a considerable distance. I propose to give here a sketch of its outcrop and some account of exposures not previously noticed. The district here treated of is contained in the 1-inch quarter-sheets of the Geological Survey, Nos. 51 north-west & south-west (western part) and 52 north-east & south-east (eastern part), and in the New Series Map Sheet 187 (not yet published). From Prof. Seeley's 1 papers the following description of the Elsworth Rock at Elsworth may be extracted:— It is known to occur throughout the village of Elsworth, passing southward under Ampthill Clay with three whitish-grey stonebands. Prof. Seeley ( op. cit. ) also recorded rock-beds of type similar to the Elsworth Rock from wells at Bourn (3 miles south-south-west of Elsworth), Papworth Everard, and Conington ; but he considered that the rock at the latter two places belonged to a lower horizon than that of Elsworth. In a brickyard west of St. Ives a like rock has long been known (the St. Ives Rock); in other brickyards north and north-east of St. Ives beds of rock were noticed by Prof. Seeley as dipping eastward, and these he was inclined to think were continuous with the Rock west of the town. A collection of fossils in the Woodwardian Museum, agreeing closely with the fauna of the Elsworth and St. Ives Rock, was supposed to have come from Holywell, but the occurrence of the limestone