Man and the Glacial PeriodWright, G. Frederick (George Frederick)
History
Man and the Glacial Period
Wright, G. Frederick (George Frederick)
Glacial epoch; Prehistoric peoples
"Bearing these facts in mind, it is surely too much to expect that
marine ice should transport boulders (how it picked up many of them also
requires explanation) with such unfailing regularity that it can be said
without challenge,[BQ] 'boulders in this district [South Lancashire and
Cheshire] never occur to the north or west of the parent rock.' The
same rule applies without a single authentic exception to the whole
area covered by the eastern branch of the Irish Sea Glacier; and hence
it comes about that not a single boulder of Welsh rock has ever been
recorded from Lancashire.
[Footnote BQ: Brit. Assoc. Report, 1890, p. 343.]
"_The Solway Glacier._--The pressure which forced much of the Irish Sea
ice against the Cumbrian coast-line caused, as has been described, a
cleavage of the flow near Ravenglass, and, having followed the southerly
branch to its termination in the midlands, the remaining moiety demands
attention.
"The 'easting' motion carried it up the Solway Frith, its right flank
spreading over the low plain of northern Cumberland, which it strewed
with boulders of the well-known 'syenite' (granophyre) of Buttermere.
When this ice reached the foot of the Cross Fell escarpment, it suffered
a second bifurcation, one branch pushing to the eastward up the valley
of the Irthing and over into Tyneside, and the other turning nearly due
southward and forcing its way up the broad Vale of Eden.
"Under the pressure of an enormous head of ice, this stream rose from
sea-level, turned back or incorporated the native Cumbrian Glacier
which stood in its path, and, having arrived almost at the water-shed
between the northern and the southern drainage, it swept round to the
eastward and crossed over the Pennine water-shed; not, however, by the
lowest pass, which is only some 1,400 feet above sea-level, but by the
higher pass of Stainmoor, at altitudes ranging from 1,800 to 2,000
feet. The lower part of the course of this ice-flow is sufficiently
well characterised by boulders of the granite of the neighbourhood of
Dalbeattie in Galloway; but on its way up the Vale of Eden it gathered
several very remarkable rocks and posted them as way-stones to mark its
course. One of these rocks, the Permian Brockram, occurs nowhere _in
situ_ at altitudes exceeding 700 feet, yet in the course of its short
transit it was lifted about a thousand feet above its source. The Shap
granite (see radiant point on map) is on the northern side of the east
and west water-sheds of the Lake District, and reaches its extreme
elevation, (1,656 feet) on Wasdale Pike; yet boulders of it were carried
over Stainmoor, at an altitude of 1,800 feet literally by tens of
thousands.
Public-domain text, read in full here on John Shaqi.
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