PEE-CARBONIFEROUS FLOOR OF THE MIDLANDS. 
107 
It will be seen that in lithological character and palaeon¬ 
tological contents the resemblance to the Midland Bnnter is 
very close. Of the nineteen species of bracliiopods found 
near Birmingham, eight are known from Budleigh Salterton ; 
and the accompanying fossils are also very similar. From 
general considerations the Devonshire geologists have been 
led to assign the rocks from which the Budleigh pebbles were 
derived to a position somewhere in the English Channel, but 
it seems to me quite possible that they may have come from 
the north-east; the ancient Midland land barrier—isthmus 
like—yielding a supply of rock-fragments (though not 
necessarily contemporaneously), both to the north and to the 
south. 
At a later period—early in Tertiary times—the Oldhaven 
Beds of Kent and Surrey show a mass of flint pebbles 
(derived from the chalk) with which, in a sandy matrix, 
are many contemporaneous marine fossils. 
At the present day the famous Cliesil Beach of Dorset, 
the Caliore Beach near Wexford, and the similar beaches 
which fringe Lake Superior afford instances of vast accumu¬ 
lations of well-rolled pebbles produced by the action of 
currents and tides, aided by the configuration of the land. 
Underground Extension of the Pre-Carboniferous Rocks .— 
It goes without saying that the isolated outcrops of Lauren - 
tian, Cambrian, and Silurian rocks, which we have described 
as occurring between Chain wood and the Mai veins, must 
be connected underground by a continuation of the strata. 
Of the presence and position of these pre-carboniferous rocks 
we have had evidence afforded by several borings. In the 
first place it seems pretty clear that these three great 
geological formations were once continuous over the Midland 
area, and that where the Cambrians are absent, and we come 
upon Silurian, or where both Cambrian and Silurian strata 
are wanting, and the borehole enters the Arcliaeans, it is 
because one or both of the newer formations has been 
removed by denudation in post-Silurian times. Secondly, 
there is an absence of rocks of tlie type of the Old Bed 
Sandstone. Strata belonging to the coeval Devonians have, 
however, been reached in the borings at Turnford, and 
in London, and it is probable that these include a band of 
quartzite, from which the fossiliferous pebbles that occur in 
the Midland Bunter, with such Devonian species as Sp infer a 
Verneuihi, have been derived. Thus the first appearance of 
the Midland Axis, or land barrier, was probably during 
Devonian times, and this land had its southern margin 
somewhere along the Charnwood-Malvern line. 
