BONNE Y : ON THE ORIGIN OF THE BRITISH TRIAS. 3 
in that direction and towards the east, for it does not occur 
on the northern shore of the Bristol Channel or in the neigh- 
bourhood of Manchester and Stockport (having thinned down to 
250 feet even at St. Helens), of Leek, the Potteries, Ashbourne, 
Derby, Wolverhampton, on the southern margin of the Clent 
and Lickey Hills, and on the western or northern side of the 
South Staffordshire coalfield. But it forms " a continuous 
though narrow band extending through Nottingham into York- 
shire." It is usually a soft friable rather homogeneous sandstone, 
of reddish bro^vn, yellow, and bright red colours, often showing 
very marked current- bedding, the laminae of w^hich, in the 
Bridgenorth district, dip towards the south-east ; it is said 
to be " entirely devoid of pebbles," and beds of w^ell-rolled 
sand grains are a rather frequent characteristic. These also 
occur in its Flintshire representative, w^here, according to 
Professor Hull, they are sometimes as large as mustard seed. 
The pebble beds occupy a wider area, generally overlapping 
the Lower Sandstone. They attain in the neighbourhood of 
Liverpool the great thickness of 1,000 feet, though here sand 
dominates over pebbles, are about 300 feet thick in the neigh- 
bourhood of Trentham and on Cannock Chase, but die out 
along a hne drawn south-east through Leicester. But they 
appear in Nottinghamshire, where their thickness is said to be 
also about 300 feet and can be traced northward through Sher- 
wood Forest iuto Yorkshire. The base sometimes is rather a 
breccia than a conglomerate. Throughout the mass we find 
current- bedding and occasional sandy partings, more or less 
lenticular, the dominant colour being red or reddish-grey. 
The Upper Sandstone is generally well developed in South 
Lancashire and Cheshire, being about 500 feet thick near Wigan, 
perhaps a little more at Liverpool, from 300 to 250 about Wolver- 
hampton and Birmingham, becoming rather less at Grinshill 
in Salop, though it may be traced southward as far as the 
Abberley Hills. In Cheshire this group also thins towards the 
east ; it is not found along the borders of the Warwickshire 
and Leicestershire coalfields, and is commonly not represented 
*' along the band of country which stretches in a northerly 
direction from the valley of the Trent at Nottingham to the 
