412 SIMPSON : STRATA AND DEPOSITION OF THE MILESTONE GRITS. 
worked. A seam, a foot or two in thickness, has been worked near 
Meltham ; and one under the Addingham Edge Rock has been 
worked and found as thick as five feet, but the instances are few 
where the beds of the series have been worth mining. Some of the 
beds have an accompanying hard siliceous seat-earth, very like the 
ganister both in composition and appearance, as it is permeated with 
stigmarian rootlets ; it is known locally as Calliard or Galliard. 
There are also one or two good fossiliferous zones with marine shells 
and nodular bands in the shales, containing Goniatites, Aviculopectens, 
Posidonomya, Nautili, &c, and occasional fish remains. 
The shales known as "binds" are of all kinds, blue or black, 
where they contain more or less carbonaceous and organic matter ; 
with a greater admixture of arenaceous matter they become stone 
binds ; or softer and more shaley, they are called soft binds. 
The Rough Rock is in the Halifax district immediately under- 
laid by, and almost inseparable from, beds of flagstones. These are 
the Second Grit of the Memoirs and are extensively quarried for flags, 
though they are often much false-bedded. This rock is probably the 
equivalent of the Haslingden flags of Lancashire. 
About Keighley, the rock correlated with this flagrock, puts on a 
peculiar form, and is known locally as the blues. It is found as a 
band of hard, blue, closely-grained rock, and is used for road mending. 
These Middle Grits occupy the tracts of high lands west of Halifax, 
from Sowerby Bridge to Blackstone Edge. The deep valleys of Calder- 
dale, Luddenden, and others are cut through the rocks of this group. 
Some of the flagstones display good worm tracks and castings, ripple 
markings, and other indications of the littoral nature of these deposits. 
Northwards, the Oxenhope and Haworth Moors, attaining to a 
height of over 1,400 feet, are on these Middle Grits, with a sequence 
gradually changing from that of the Halifax neighbourhood to the 
one more characteristic of Skipton and Keighley. Keighley itself is 
partly built on the rocks of this group. From Silsden Moor the 
Addingham Edge Grit, a coarse massive member of the Middle Grits, 
may be traced round the flanks of Rombald's Moor to Ilkley, where it 
forms the picturesque and well-known Cow and Calf Rocks. Further 
in the same direction it is the rock of Otley Chevin, Arthington 
