SUBTERRANEAN GEOLOGY OF SOUTH-EASTERN ENGLAND. 153
Thames or north of it. Here, for the first time, we meet with
considerable difficulties in the way of a certain identification of
the various rocks—at least, in three cases. The borings about
which there is no doubt as to the age of the rocks at the
bottom are : — Harwich (Lower Carboniferous), Ware (Upper
Silurian), Turnford (Devonian), and Meux's Brewery (Devonian).
But as regards the remaining three there is considerable difference of
opinion. At Kentish Town, Richmond, and Crossness, the rocks in
which the borings ended were of a red and mottled character, and
the absence of fossils, which are generally very scarce in beds of a
red colour, has prevented any decided conclusions as to their age on
the part of the able geologists who have examined the boring cores.
For the lithological character of these red rocks would furnish but an
uncertain guide to their affinities—as determined by an inspection of
boring cores—did they come to the surface within 20 miles of
London, and becomes a more and more uncertain test in pro-
portion as the position of their outcrop exceeds that distance.
At Richmond the boring ended after piercing through 208 feet of
beds consisting almost entirely of red and mottled sandstone, which
appeared to be much false-bedded. It was a task of some difficulty
to distinguish between this false-bedding and true dip, but Prof.
Judd is decidedly of opinion that the true dip was about thirty degrees.
He remarks that this high dip, with the natural inference that these
red and mottled sandstones are unconformable to the Jurassic and
Cretaceous beds above, may be regarded as telling in favour of their
pre-Carboniferous age, but adds that it is by no means impossible
that the Poikilitic (Permian and Triassic) strata in this district were
disturbed and denuded before the deposition of the Great Oolite.
He also thinks the lowest beds in the boring much more like the
New Red than the Old Red Sandstone. Mr. Whitaker is inclined
to agree with Prof. Judd in thinking them Triassic, while Prof.
Prestwich, on the other hand, considers them more likely to be Old
Red Sandstone.
With regard to Kentish Town, Prof. Prestwich remarks that
he found on comparing the Old Red Sandstone in the neighbour-
hood of Frome with the Kentish Town specimens, that the latter
"agreed closely with the Mendip Beds in lithological characters,
whereas there was, on the whole, a want of agreement with the
Permian or Triassic series." He adds—"I was confirmed in this
view after seeing the Red Sandstones and Marls, belonging to the
L