358 Mr. Horner o« />&<? Geology of the 



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 grau- 

 wacke series, of limestone and of quartz, united by a calcareo-argil- 

 laceous cement of a reddish brown colour. The limestone is In 

 general grey with a reddish tinge, of a crystalline texture, with 

 laminae of calcareous spar scattered through it, and frequently con- 

 taining carbonate and sulphuret of copper j 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 brown- 

 ish 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 



