354 DAKYNS : LOWER CARBONIFEROUS ROCKS IN YORKSHIRE. 
Going northwards this type undergoes great changes ; the second 
grit is merely a basement bed to the Rough Rock, from which it cannot 
always be separated ; the third grit loses its massive character in 
many places ; and other beds of sandstone show themselves amid the 
shales overlying the Kinderscout grit. 
In the valley of the Colne there are four sandstones between the 
Rough or Sand Rock and the recognised Kinderscout grit ; the same 
is the case ni the valley of the Yorkshire Calder ; but in the basin 
of the Aire the series consists in descending order of the following 
beds : First, the Rough Rock, which maintains throughout its usual 
character till it is lost to sight beneath the Permians ; seccondly, a 
very variable basement bed to the last, consisting generally of flag- 
stones. Below this comes a series of variable sandstones and shales, 
sometimes containing as many as fifteen or sixteen distinct beds of 
sandstone between the Rough Rock and the regular Kinderscout 
grit. This set of beds may, however, be conveniently divided into 
two by means of the massive grit of Hallan Hill and Earl Crag, which 
is continuous with the third grit of Lancashire. It is this rock 
which, according to the mapping of Mr. Lucas, forms the well-known 
Brimham Rocks, near Pateley Brig. 
Owing to the number of sandstones that have now come in, it is 
somewhat uncertain what ought to be taken as the top of the Kinder- 
scout grit ; but there is no doubt whatever about the main mass of 
the bed, for it retains throughout the country its character of a very 
coarse and massive grit, forming crags and stacks of rock. It is 
underlaid by a thick but variable series of sandstones with shale 
partings. As there is ofttimes no definite line of separation between 
these beds and the Kinderscout grit, we now classify them with the 
millstone grit, and call them Pendle grits, because they form the 
chief features of that conspicuous hill. Below them lie the Black 
Bolland shales, at the base of which comes sometimes what 
Mr. Tiddemau has called the "Lower Yoredale Grit."' In litho- 
logical character the beds of this grit answer very well to certain 
hard silicious sandstones of the Yoredale series, known to miners as 
Dirt Pot grits. In the neighbourhood of Skipton the Kinderscout 
and Pendle grits are underlaid by a great thickness of shales con- 
