Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/361

 did not continue driving the level, but worked in the limestone on all sides The mine has however been abandoned, as the produce was not sufficient to bear the expense of an engine to drain off the water.

§ 17. I found specimens of the black slaty limestone at the mouth of the pit, and I afterwards observed the same stone in the limestone quarry near Ely green interposed between the beds of limestone. It is of a coal black colour, but becomes white when heated: dissolved in muriatic acid it leaves a black powder, and this powder when heated is partly dissipated, and what remains is a white earth. The limestone appears therefore to owe its black colour to carbonaceous matter.

Besides the quarries I have named there are several others, but as they present no appearances different from those I have already described, it is not necessary to do more than mark their occurrence on the map.

§ 18. About a furlong eastward of Halsey cross, in a quarry where stones are obtained for mending the roads, I found strata of the coarse grained and slaty varieties of the grauwacke formation, alternating with a calcareous rock different from any other I had seen in this district. Its colour is in general reddish brown, very similar to the strata that alternate with it, but the calcareous strata are not all alike. In none of them are there any traces of organic remains, unless indeed some detached crystalline laminæ may be considered as indications of them. The principal varieties are