. i^^ ^ ^y ^^ I.—GEXERAI, VIEW OF .\ - MIDDLE CHAEK " QUARRY. situated four to six miles south of the Humber. Here the chalk comprises what geologists call the " Middle " Chalk, which is of a very different character from that of the " Lower " Chalk at Barton. The Middle Chalk contains a great deal more flint than the Lower Chalk. The previous article described how the pure, almost flintless chalk was mixed with river mud or clay and burnt to Portland cement at the works erected on the Humber side. But inland, not only are there no facilities for water-transport, but t
. i^^ ^ ^y ^^ I.—GEXERAI, VIEW OF .\ - MIDDLE CHAEK " QUARRY. situated four to six miles south of the Humber. Here the chalk comprises what geologists call the " Middle " Chalk, which is of a very different character from that of the " Lower " Chalk at Barton. The Middle Chalk contains a great deal more flint than the Lower Chalk. The previous article described how the pure, almost flintless chalk was mixed with river mud or clay and burnt to Portland cement at the works erected on the Humber side. But inland, not only are there no facilities for water-transport, but there is little or no suitable clay at the surface, and the chalk is usually fuU of flint either in the form of smooth nodules, some of which attain a diameter of 3 or 4 feet and are called of gelatine. These chemicals separate out into well- deftned rings comparable to flint, those at the middle of the test-tube being near together, while those farther from the middle are farther apart ; the bands being absent altogether at the top and bottom. In Lincolnshire the " Lower Chalk " consists of a greyish-white flintless chalk arranged almost horizon- tally in beds or layers 50 feet thick. This is divided from the " Middle Chalk " by a band of marl (chalky clay) about 2 feet thick. The " Middle Chalk " is a hard white chalk 100 feet thick with scattered flints and layers of flint-nodules in the upper part. The " LTpper Chalk " has onlj- comparativeIj' recently been dis-
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