612 EEPOBT— 1886. 



other indurated arenaceous rocks which occur in the conglomerate, especially from 

 those containing fossils. 



The above-descrihed quartzites differ in appearance hoth macroscopically and 

 microscopically from those of Plartshill, the Lickey, and the Wrekin district, 

 but they closely resemble the most compact variety, which I have already described 

 as occurring in boulders in coal. They have also an extraordinary likeness to 

 quartzite pebbles in Old Red Sandstone and Lower Carboniferous conglomerates of 

 Southern Scotland and to the quartzites of the northern and western Highlands, 

 already described, a liver-coloured variety of which, as I have been informed, occurs 

 in the island of Jura. These quartzite pebbles, to my knowledge, may be traced 

 into Lancashire on the one side of the Pennine chain and to beyond Retford on the 

 other. The quartz-felspar grit consists mainly of quartz and felspar, obviously the 

 debris of granitoid rock. I have found it at various localities on the northern 

 margin of Cannock Chase and have received specimens from the Bunter beds near 

 the Lickey and near Nottingham. The rock, macroscopically and microscopically, 

 presents an extraordinary resemblance to the Torridon sandstone of North-west 

 Scotland, and differs from every other rock which I have seen in situ in any 

 other part of Britain. The nearest approach to it is the quartz-felspar grit, already 

 mentioned as ha\ing been sti-uck in the Gayton boring, Northamptonshire, but this 

 has a calcareous cement. The felstones vary from micro-crystalline to glassy rocks 

 more or less devitrified, some being slightly scoriaceous. They may be classified 

 lithologically as quartz-felsites, rhyolites (more or less devitrified), quai-tz-porphy- 

 rites, porpbyrites, and old andesites. Some specimens contain a considerable 

 amount of tourmaline, and I have seen this mineral in the vein-quartz pebbles. It 

 also occurs rather abundantly in a very hard, black quartzose grit. I have received 

 varieties of felstone, which I have found on Cannock Chase, from the Bunter beds 

 of the Lickey and from Nottingham. In Staffordshire pebbles of granitoid rock, 

 gneiss, and schist are not only rare, but also generally too rotten to admit of ex- 

 amination ; but I found, a few months since, in the conglomerate at Style Cop, near 

 Rugeley, two pebbles of a whitish gneiss, which appeared to me to indicate a 

 secondary cleavage-foliation, such as may be observed in many parts of the 

 Scotch highlands. The black quartz-schist already mentioned exhibits a peculiar 

 ' squeezed-out ' structure, which ordinarily indicates that the rock has undergone 

 great pressure. 



The sandy matrix and associated sandstones of the conglomerate beds, together 

 with those of the Upper and Lower Bunter, and of the Lower Keuper, consist 

 mainly of quartz grains, most of which appear to have been derived originally from 

 granitoid rocks. They are often more or less angular, but at certain horizons, as 

 described by Dr. Sorby, Mr. Phillips, Mr. G. H. Morton,' and others, well-rounSed 

 grains are so abundant as to suggest an exposure to the action of the wind. They are 

 often stained red with iron peroxide, and mixed with more or less earthy matter. 

 In Cheshire and Ijancashire recognisable grains of felspar have been noticed by Mr. 

 Morton and others, and probably this mineral is, in most cases, the source of the 

 argillaceous constituents which are often intermingled with the quartz grains. Flakes 

 also of white mica are sometimes rather common. So far as I have been able to 

 judge, distinct grains of rolled felspar are commoner in the north-western district 

 than in Staffordshire, where, however, mica-flakes are sometimes rather abundant. 

 The Keuper sandstones seem to me to differ from the above only in the general 

 absence of the red colour, and in a more even bedding, especially towards the 

 upper part (the wat erst ones), where they are interbedded with the marls. The 

 appearance of these last suggests that the currents were gradually losing strength, 

 and only capable of transporting the finer felspathic detritus with occasional tiny 

 plates of mica. 



The lithology of the lower part of the Trias in the southern area is as yet 

 imperfectly worked out, and a rich harvest awaits the student. My own know- 

 ledge of it is but superficial, so that I must pass it by with a brief notice. The 



' In an excellent paper published in the Proceedings of the Liverpool Geological 

 Society, vol. v. p. 52. 



