166 
PRE-CARBONIFER.OUS FLOOR OF THE MIDLANDS. 
The Jurassic System lias an uninterrupted outcrop from 
Dorset to Yorkshire, crossing the old land, and probably 
filling up one of its valleys, near Northampton. But neither 
Liassic nor Oolitic strata have any eastward extension, for the 
borings prove their absence, except in the most fragmentary 
form, between Ware and Richmond. 
Fragments of the Pre-Carboniferous Floor contained in newer 
rocks .—The Carboniferous strata of the Midlands contain but 
few rock-fragments or pebbles of the formations upon which 
they rest. This is not a matter of surprise when we remember 
that the mountain limestone is a deep-water formation, whose 
actual junction with its southern shore-line is nowhere ex¬ 
posed, although we approach within a hundred yards or so of 
it at Gracedieu, on Charnwood Forest.* 
The Millstone Grit of Stanton Harold and Ticknall 
(N.W. Leicestershire) is only 200 feet thick, and contains a 
quartzitie conglomerate. Much of the rock may be termed 
“ arkose,” the cemented felspar and quartz crystals of which 
it is composed having suffered very little wear. 
The coal-measure shales must have been deposited in very 
quiet waters—perhaps in the swamps and deltas of the many 
mouths of a mighty river like the Amazon or the Mississippi. 
No bare rocky ledges or abrupt sea-cliffs existed along the 
shore-line to furnish shingle beaches, but monotonous Hats, 
formed perchance by the Silurian shales. 
In Leicestershire the Permians exist only as thin patches 
of breccia, consisting of green slates, grits, quartzites, and 
greenstones, some of which are polished and striated. The 
so-called Permians of the Warwickshire coal-field I believe to 
be largely upper coal-measures. 
In Staffordshire the Permians of the Clent Hills are so 
charged with rock-fragments that these heights were formerly 
thought to consist of solid trappean rock. Near Nortlifield 
the same strata are crowded with angular blocks of Silurian 
limestone and sandstone, quartzite, &c., so that Prof. Jukes 
(who surveyed the district) was compelled to the belief that 
“ a boss, or peak, or ridge of the Silurian sandstone lies 
concealed under the Permian rocks somewhere close by.”f 
In Shropshire the Permian breccias of Alberbury west of 
Shrewsbury, consisting of angular fragments of Silurian and 
Lower Carboniferous rocks, are no less than 400 feet thick. 
* The actual junction is here hidden by a patch of Triassic sand¬ 
stone, which rests unconformably on the edges of the Forest rocks and 
the limestone. 
f Geol. S. Staff. Coal-field, p. 9. 
