TRANsiACTIONS OF SECTIOI^ C. 609 



had not been drifted from far. A few also appear to have heen derived from 

 schists. From what I have myself seen I anticipate that Dr. Sorby's conclusions 

 may be extended to most of the other coarser Carboniferous clastic beds of Northern 

 England, except that, perhaps, as was inferred by Professor Hull, another impor- 

 tant, if not the principal, source of supply must be sought on the north-west. The 

 materials of the basement conglomerates and grits in North Wales appear to be 

 either Paleozoic rock or vein-quartz and an impure jasper ; but a microscopic 

 study of carefully selected specimens, especially from Anglesey, might produce 

 interesting results. In Central England, as the Old Red Sandstone is commonly 

 absent, and, if present, must have been speedily buried, we should naturally look 

 farther afield for the materials of the Coal Measure sandstones and Millstone grit, 

 where it occurs. But probably we shall be right in including this, as indicated by 

 Professor Hull, with the nortbern district. He also points out that in the south- 

 western part of England and in South Wales there is good evidence that the materials 

 have been brought by currents from the west. I have only examined one specimen 

 from this region, but it has proved very interesting. It is from a Carboniferous grit 

 near Clevedon, in Somersetshire. About one-third of the rock consists of quartz 

 grains which I should suppose derived from schists or gneisses of moderate coarse- 

 ness ; quite another third of fragments of a very fine-grained micaceous schist, 

 about -0.3" long. It is possible that these may be phyllites, but I think it far more 

 probable that they are true schists. They are very like some of the more minutely 

 crystalline schists of Anglesey, and it is evident in some cases that the rock had 

 been corrugated subsequent to foliation. This grit also contains a few bits of 

 felspar and flakes of mica. I must not forget to mention some curious boulders 

 which have been discovered occasionally in actual coal-seams. Through the kindness 

 of Mr. RadclifFe I have been able to examine some specimens found at Dukinfield 

 Colliery. They are hard quartzose grits and quartzites, bearing a general resem- 

 blance to sundry of the earlier Palaeozoic rocks. One of the latter is as compact 

 and clean-looking as the well-known quartzite of the north-western Highlands. 

 Besides quartz, and perhaps a little felspar, it contains a small quantity of iron- 

 oxide (?), two or three flakes of white mica, a grain or two of tourmaline, and of a 

 mineral resembling an impure epidote. A similar quartzite has been found by 

 Mr. W. S. Gresley in a coal-seam in Leicestershire, and I have described another 

 from the ' thirteenth coal ' at the Cannock Chase Colliery. In each of these 

 quartzites the two minerals last named may also be detected. 



Before quitting the Carboniferous series I must call attention to some interest- 

 ing grits which during the last few years have been struck in deep borings. In 

 the London district a red sandstone, in some places conglomeratic, has been found 

 underlying sundry members of the Mesozoic series. Some have thought this of 

 Triassic age, but inasmuch as it is very doubtful, as we shall presently see, whether 

 the coarser beds of the Triassic formations extended so far to the east, and the dip 

 of the red beds in the well at Richmond agrees better with that of the Palaeozoic 

 rocks in other parts of the buried ridge, I think these sandstones more probably 

 older tban any part of the Mesozoic series, perhaps not very far away from the base 

 of the Carboniferous. In the boring at Gayton, in Northamptonshire, Lower Car- 

 boniferous rocks were succeeded by reddish grits and sandstones. The finer beds 

 much resembled the ordinary Old Red Sandstone, and, like it, suggested a deriva- 

 tion from fairly coarse-grained crystalline rocks. But of the origin of one rock, a 

 quartz-felspar grit, there can he little doubt. I may briefly describe it as very like 

 the Torridon sandstone of Scotland, except that the cement is calcareous. I do 

 not, indeed, claim for it a like antiquity, for I think it far more probably about the 

 age of the lowest part of the Carboniferous series ; but it, too, must have been 

 derived from granitoid rocks. "While some of the grains are fairly well rounded, 

 others, especially of felspar, as in the Millstone grit of South Yorkshire, do not 

 seem to have travelled very far. 



Permian. — The sandstones of the northern area belonging to this formation do 

 not, as far as I have been able to ascertain, afibrd us much information. Quartz 

 grains, of course, abound, but as they are rather small, it is not possible to be sure 

 whether they have been primarily derived fi'om a granitoid rock or a schist. The 



1886. E R 



