392 DK. W. HIND AND MR. J. A. HOWE ON THE [Aug. IQOI, 



We have adduced stratigraphical evidence that, north and west of 

 Pendle Hill, this series rapidly diminishes in thickness, till in the 

 Isle of Man only a few feet of black shales and limestones represent 

 the great thickness seen in Pendle. To the south also, in Stafford- 

 shire and Derbyshire, we have shown this series to have become 

 much thinner. We know that the series is absent in Shropshire, 

 South Staffordshire, North Wales, and probably Leicestershire. To 

 the north, if represented at all, the beds are much thinner and 

 not easily recognized. 



The important fact to be noted in connection with the distribu- 

 tion of the Millstone Grits and the Pendleside Group is that the 

 maximum area of deposition of both coincides with each other and 

 with the area in which the limestone is thickest and undivided. 

 That is to say, the British Carboniferous rocks were laid down in a 

 basin, the greatest depth of which was approximately in the Northern 

 Midlands. 



Unfortunately the size of the grains and included pebbles in the 

 various beds of the Millstone Grit is so variable and local that it does 

 not permit of any definite conclusion as to their direction or source 

 of origin, but the pebbles in the Kinderscout Grit do become larger 

 as the beds pass eastward. The Calciferous Sandstone Period is the 

 Carboniferous Sandstone or Grit age of Scotland and the North of 

 England ; the pre-Coal-Measure period represents the great deposit 

 of detrital quartz in North Central England. Do these facts help 

 us to determine anything as to the source whence the beds were 

 derived ? Although the granites of the Highlands of Scotland are 

 a possible source of the Calciferous Sandstone Series, the Millstone 

 Grit Series is certainly not connected with this district by beds 

 which thicken as they pass northward, nor are the Grits coarser in 

 that direction. A western source may certainly be negatived, for the 

 beds all appear to die out to the west, and the same condition 

 obtains southward. 



The Carboniferous sequence in Belgium shows a thick mass of 

 limestone separated from the Coal-Measures by only a very small 

 group of beds, which contain the fauna of the Gannister Series. 

 Evidently this area was altogether outside the region of grit-deposition. 

 By a process of exclusion, therefore, the pebbles and quartz of the 

 Millstone Grit Series could only have been derived from land lying 

 to the east and north-east, probably from a continent which in- 

 eluded the Highlands of Scotland and Scandinavia. The source of 

 the Millstone Grits must have been largely a granite-area, for mica 

 and felspar, the latter sometimes decomposed into a china-clay, are 

 found abundantly in certain of the beds. The Pendleside Group 

 probably was derived from the same direction, and was laid down 

 farther from the shore than the Millstone Grit, and therefore the 

 whole of the deposits indicate a slowly-rising area. 



On the other hand, the migrations of faunas, the geographical 

 •situation of the beds, and the stratigraphical evidence point 

 strongly to a more directly northern source for the shales and sand- 



