SPENCER : THE YOREDALE AND MILLSTONE GRIT ROCKS. 383^ 
occur in it, such as Lejndodendron obovatum, L. aculeatum^ Stern- 
bergia (Artisia), Sigillaria tessellata, Halonia regularis, ferns, 
Cauleopteris, Stigmaria ficoides, numerous fruitstones, Calamites, &c. 
All the sandstone beds contain fossil plants in places, and 
many of the shales also yield them, but those which occur at or 
near the surface of the shales are seldom well enough preserved 
for specific distinction. 
The A grit has a greater surface range than any of the other 
Third Grits. It forms the surface rock of Warley and Saltonstall 
Moors, and thence runs round the head of Luddenden valley to 
the upper end of Wadsworth Moor; also that of Crow Hill on 
Sowerby Moor and other places. This grit, like all the other Third 
Grits, is liable to thin away and deteriorate into rag and shale. 
It is a typical grit on Warley Moor, but in Wheatley valley, a 
mile and a half to the south east, it has become a mass of bedded 
rag and shale. This rock crops out in Brimsroyd Clough, Norland, 
where the upper part consists of raggy stone in beds of from 
1 to 2 feet thick, and the lower part of a mass of thin slaty 
layers, each from ^ inch to 2 inches thick. The T) rock 
furnishes us with another example of this character, for from 
200 feet at Hathershelf Scout it dwindles down to 50 or 60 feet 
at Higham, in Sowerby, in a distance of about a mile and a quarter. 
The Third Grits spread over a large area of the moorlands on each 
side of the Calder, and reach the height of 1,350 feet on Warley 
and Wadsworth Moors, 1,150 feet on Crow Hill, Sow^erby, and 
1,369 feet on Manshead. 
Rough Rock. 
The Rough Rock is a massive grit of from 100 to 150 feet in 
thickness. This estimate includes the shales and flagstones under- 
lying it, which in this district form part of it. It ranges from Nab 
Hill, 1,470 feet above sea level on Oxenhope Moor, down by Hunter 
Hill to Halifax, where it sinks under the Lower Coal Measures, and 
to Elland where it is covered by the alluvium of the valley. It also 
forms the surface of Norland and Greetland Moors. 
