Yol. 56.] BUNTER PEBBLE-BEDS OF THE MIDLANDS. 297 



becomes pebbly in places, not, however, including, so far as we saw, 

 such well-marked beds as those just mentioned. In the neighbour- 

 hood of Castle Pulverbatch we found them becoming fine-grained, 

 and interbanded with the usual argillites of the Longrnynd. 1 



The following extract from my diary will show the impression 

 produced by walking over a considerable area occupied by these 

 beds 2 : — ' On the whole, I am doubtful whether this can be the 

 region which has supplied the quartz- felspar grit to the Stafford- 

 shire Bunter. The rock is more liable to small changes in the course 

 of an inch or so ; much of it is apparently rather richer in mica 

 (biotite) ; the grains are perhaps a little more rounded than in the 

 Bunter grit or in the normal Torridon ; the quartzite in the pebbles 

 differs slightly from that common in the Bunter conglomerate, though 

 some varieties may be identical ' (I did not see the ' liver-coloured 7 

 kind). Other difficulties are then mentioned, which I pass over for 

 the moment. I collected a few specimens, including those which 

 were most like the quartz-felspar grits of the Scottish Torridonian 

 and of the Bunter Pebble-bed. These I have examined under the 

 microscope. The first of them came from the middle of the lower 

 conglomerate (No. 1) near Lyds Hole, and is very like the coarse 

 Torridon Sandstone between Kinlochewe and the Loch Maree 

 Hotel. It contains grains of dusty-looking quartz and of felspar 

 (not much) : both being probably derived from a coarse granitoid 

 rock. (They are associated in one fragment, and another shows a 

 micropegmatitic structure.) We find also some grains of composite 

 quartz (? from veins) and many representing varieties of devitrified 

 rhyolites. 3 The next specimen came from the Upper Torridonian on 

 the way from Plealey to Castle Pulverbatch. Though it was not 

 in situ, I took it because it more closely resembled a piece of 

 ordinary Torridon Sandstone than any other which I found. Under 

 the microscope we find that the fragments are more or less sub- 

 angular, often about *03 inch or a little less in width ; quartz is fairly 

 common, both in single and composite grains (the latter generally 

 from veins, but possibly also from a crystal] ine rock) ; very little 

 felspar occurs, but there is an abundance of fragments of volcanic 

 rocks, some rhyolitic, many more or less ferrite-stained, and several 

 blackened with opacite. One or two include spots of viridite, but 

 the presence of cavities is doubtful. (See PI. XX, fig. 6.) 



The remaining specimens do not strikingly resemble Torridon 



1 An enumeration of the contents of the pebble-beds of this series (which I 

 have only recently read) is given by the Eev. J. F. Blake, Quart. Journ. Geol. Soc. 

 vol. xlvi (1890) p. 398. My description is condensed from the notes written 

 on the spot. 



2 Eocks resembling these, if they occur at all in the Staffordshire Bunter, 

 are inconspicuous. Perhaps I should add that the quartzite of the Stiper 

 Stones differs from the one typical of the Pebble-bed. 



3 I use the term rather loosely, to indicate rocks like those which occur about 

 the Wrekin and near Pontesbury : that is, compact red lavas, varying probably 

 from rhyolites to dacites, and perhaps sometimes not quite so rich in silica. A 

 more precise determination would be needless, and often impossible without 

 chemical analysis. 



