302 Mr. Horner ott the Mineralogy of the Malvern Hills. 



rock composed of hornblende and mica, intermixed with a small 

 quantity of felspar, quartz, and pyrites. It .occurs in large masses 

 irregularly heaped together, and the relative position of the schistose 

 structure in the different masses preserves no uniformity. It is tra- 

 versed by granite veins, varying from one to six inches in thickness, 

 branching in different directions, and diminishing in thickness as 

 they ascend. This schistose rock is very similar to one that occurs 

 by the side of the road leading up to the Wych, where it is also 

 traversed by granite veins. 



§41. A deep but narrow valley separates Swinnit Hill from the 

 Holly-Bush Hill. In this valley, and in the lower part of the latter 

 hill, I found the following rocks : 



a. Different varieties of gneiss, imperfectly characterized. It 

 seems to bear the same relation to true gneiss, that the granite of these 

 hills has been described to bear to Alpine granite. 



b. A fine grained sandstone, consisting principally of quartz, with a 

 few particles of felspar and mica : in some places it includes large 

 rounded fragments of quartz and felspar, having the appearance of a 

 breccia. 



c. Granular quartz, mixed with small white specks of decomposed 

 felspar.* 



* The same rock as this occurs in strata, by the side of the road between Bromesgrove 

 and Birmingham, and many of the pebbles of the gravel, that covers so great an extent of 

 country in that part of England, are composed of it. 



Mr. Playfair, in his Illustrations of the Iluttonian Theory, ^^ 336, 337, speaking of 

 this gravel, says, that it might in part have been produced from the detritus of these strata 

 near Bromesgrove. About two years ago, when in that part of the country, I examined 

 a great variety of the pebbles in a gravel pit, about a mile to the north of Birmingham, 

 and I afterwards examined the strata near Bromesgrove. On comparing the specimens 

 from both, I found a perfect identity between several of the pebbles and the stratified 

 quartzose rock. Between these sfrata and the gravel pit, there is an extent of about ii:n 

 niles of nearly level country. 



