Man and the Glacial PeriodWright, G. Frederick (George Frederick)
History
Man and the Glacial Period
Wright, G. Frederick (George Frederick)
Glacial epoch; Prehistoric peoples
"Six miles to the northward of Flamborough, at Speeton, a bed of
estuarine silt containing the remains of mollusca in the position of life
occurs at an altitude of ninety feet above high-water mark. Mr. Lamplugh
inclines to the opinion that this bed is of earlier date than the 'buried
cliff'; he also admits the possibility that its superior altitude may be
due to a purely local upward bulging of the soft Lower Cretaceous clays
upon which the estuarine bed rests by the weight of the adjacent lofty
chalk escarpment.
"The evidence obtained from inland sections and borings in different
parts of England has been taken to indicate a greater altitude in
preglacial times. Thus, in Essex, deep-borings have revealed the
existence of deep drift-filled valleys, having their floors below
sea-level. The valley of the Mersey is a still better example. Numerous
borings have been made in the neighbourhood of Widnes and at other places
in the lower reaches of the river, making it clear that there is a
channel filled with drift and extending to 146 feet below mean sea-level.
This, with several other instances, has been taken to indicate a greater
altitude for the land in preglacial times, since a river could not
erode its channel to such a depth below sea-level. The argument appears
inconclusive for one principal reason: no mention is made of any river
gravels or other alluvium in the borings. Indeed, there is an explicit
statement that the deposits are all glacial, showing that the channel
must have been cleared out by ice. This, therefore, leaves open the
vital question, whether the deposits removed were marine or fluviatile.
It may be remarked that the great estuary of the Mersey has undoubtedly
been produced by a post-glacial (and probably post-Roman) movement of
depression.
"_The Preglacial Climate._--In all speculations regarding the cause
of the Glacial epoch, due account must be taken of the undoubted fact
that it came on with extreme slowness and departed with comparative
suddenness. In the east of England an almost perfect and uninterrupted
sequence of deposits is preserved, extending from the early part of the
Pliocene period down to the present day.
"These in descending order are:
"1. Post-glacial sands, gravels, etc.
"2. Glacial series.
"3. The 'Forest Bed' and associated marine deposits.
"4. Chillesford clay and sand.
"5. The many successive stages of the Red Crag. (The Norwich Crag is a
local variation of the upper part of the Red Crag.)
"6. The Coralline Crag.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account