On the Occurrence of a Limestone with Upper Gault Fossils at Barnwell, near Cambridge

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Abstract
In the course of a recent examination of the great Gault-pit worked by the Cambridge Brick Company, Ltd., at Barnwell, my attention was drawn to an unusual and inconstant hard bed which is occasionally met with in the lowest part of the pit. On examination, the hard material was found to consist largely of comminuted Inoceramus -fragments, with occasional ammonites and other shells, and a careful search ill this and the adjoining clay proved them to be quite fossiliferous. Unfortunately, the specimens obtained are only fragmentary, but as they seem to indicate a horizon higher than any yet recorded from the Cambridgeshire Gault, they may perhaps be worthy of record. The section now seen is as follows, in descending order :— Of these, the three lowest divisions are the most interesting, and nearly all the fossils come from the beds (4)and (5). The Hard Band (4) is extremely variable in thickness. It occurs in a series of flattened lenticles, generally a few yards in diameter and up to a foot in thickness. It is largely made up Of broken shells and phosphate-nodules, with a few bone-fragments and extraneous pebbles of mud, and is harsh to the touch. Some of the ammonites and Inocerami are very large, and specimens of the latter 3, 4, and even 5 inches across are not uncommon. Petrologically, the Hard Band is best described as a somewhat muddy shell-limestone. It contains abundant phosphate-nodules, of which at least three types occur: these we may distinguish as the green,

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