Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/366

 the ascent, varying from a few inches to several fathoms in extent, and having in general a stratified structure.

§ 23. Near the village of Alcombe, and at the foot of one of the lateral branches of Grabbist hill, there is found a conglomerate differing considerably from either of those already described. It occupies a very small space superficially, probably not more than a square furlong, but it is found in very thick beds. It is composed of rounded fragments of the coarser quartzose varieties of the grauwacke series, of limestone and of quartz, united by a calcareo-argillaceous cement of a reddish brown colour. The limestone is in general grey with a reddish tinge, of a crystalline texture, with laminæ of calcareous spar scattered through it, and frequently containing carbonate and sulphuret of copper; characters sufficient to identify it with the subordinate beds of the grauwacke formation. In one or two instances I found it containing chert. In some parts of the conglomerate the cement is very much mixed with white and flesh coloured sulphate of barytes in crystalline plates, and with green carbonate of copper. It is also traversed by veins of calcareous spar, and contains cavities lined with crystals of the same substance. The fragments are of different sizes; some of them are as large as a man's head. The conglomerate is covered by a loosely aggregated quartzose sandstone, varying in colour from reddish white to brownish red, and often containing much calcareous matter. Sometimes there are fragments of the same varieties of grauwacke that occur in the conglomerate, found in those parts of the sandstone that are contiguous to it; and it is also mixed in some places with green carbonate of copper and with sulphate of barytes. In the upper part of the conglomerate there are rounded fragments of a sandstone mixed with carbonate of copper nearly identical with that of the beds lying over the conglomerate. This sandstone is about 5 or 6