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 traversed 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, asre composed of it.
Mr. Playfair, in his Illustrations of the Huttonian 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 strata and the gravel pit, there is an extent of about ten miles of nearly level country.