rks (_a_, p. 542), "from sea-level
up to about 400 feet, and in places 600 feet, is covered by a continuous
mantle of boulder-clay and sands." "These clays, as a rule, contain
distributed through them, in a greater or less degree, fragments of
shells and some perfect ones. I myself have recorded forty-four
species." Again he continues (pp. 545 and 546): "A large part of
Ayrshire is covered with similar shelly boulder-clays from sea-level to
1061 feet at Dippal. These Ayrshire high-level shells have, in the
majority of cases, been taken, not from sand and gravel beds, but from
boulder-clay, and in that respect they are most important and unique. In
Moel Tryfan the shells are found in sands and gravels at 982 feet; on
the range of hills from Miaera to Llangollen from 1000-1200 feet; also
in sands and gravels at Gloppa, near Oswestry, at 1100-1200 feet; and
near Macclesfield at a level of about 1200 feet. In Ireland marine
shells can be traced almost from sea-level to a height of over 1000
feet."

"Again," continues the same author, "if we look broadly at the
distribution of these shelly deposits, we find that they occur all round
our maritime coasts in Lancashire, Cheshire, and Wales, in Cumberland
and Westmoreland, Wigtonshire and Ayrshire, and along the eastern coast
of Ireland. The same is to be said of the eastern coasts of England and
Scotland."

That a very considerable change of sea-level has taken place in some
parts of the British Islands would appear to a zoologist the most
logical conclusion after an examination of these "high-level shelly
sands and gravels," but the shells contained in them are now generally
supposed to have been carried there frozen in the sole of a glacier or
pushed up in front of it. The older view, however, which agrees so much
better with the facts of distribution, fortunately has not disappeared
among geologists. "When we call up," says Mr. Mellard Reade (_b_, p.
435), "before our mental vision the simple and well-known facts of
nature which suffice to explain the marine drifts on the theory of
submergence, it seems unnecessary to resort to the ingenious and
artificial system of physics elaborated to explain the phenomena of
land-ice."

"When we have more knowledge of the glaciers of the Arctic Regions, and
facts, in place of ingenious suppositions, to base our reasoning upon,
we may possibly have to revise all our glacial conceptions. In the
meantime, the submergence theory of the o