19 
in the north of Ireland and in Scotland by sandstones, shales, 
and thick coal-seams, with occasionally a thin band of lime- 
stone. If we trace the upper boundary of it from Wharfe- 
dale to Wensleydale, we find the thin ends of several wedges 
of sedimentary strata splitting up the higher part of the 
limestone, and this subdivision continues till, as I have said, 
the limestones are nearly extinct. Between Settle and 
Derbyshire we have only the South Craven district to furnish 
us with any evidence of the changes occurring in the Car- 
boniferous Limestone. From Malham to Bell Busk and 
Gargrave we have a thick mass of impure laminated lime- 
stone, with frequent bands of calcareous shale. To the west, 
this is reversed, and we have a thick mass of shale, with 
occasionally bands of impure limestone. Then, at Skipton, 
we find a mass of thin bedded limestone, overlaid by three 
or four good thick limestones, separated by equally thick 
beds of calcareous shale, the whole being overlaid by thick 
shales, calcareous only at their base. Similar shales with 
thin limestones occur in the Calder Valley, near Todmorden. 
We now come to the Millstone Grits, which, for the sake 
of distinction we subdivide into four groups, corresponding 
to the five which occur in Derbyshire, the second (in descend- 
ing order) having died out or merged with the first. The 
lowest of these groups consists of sandstones (sometimes 
calcareous) and shales. It is the " Yoredale Grit " of Derby- 
shire, but we have dropped that name, as this group appears 
to be wanting in the Yore Valley, ^ext we have a thick 
mass of coarse grits and shales, with finer sandstones towards 
the top. This is the equivalent of the Kinder Scout Grit, of 
Derbyshire. Near Skipton it is coarser than any conglomerate 
of Carboniferous age that I have seen elsewhere. I found 
one pebble of vein-quartz weighing over two ounces, and 
measuring three inches by one and a quarter by one inch. 
This was in contact with others, averaging a spherical inch. 
