Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
and that we have abundant evidence of a great
rising of the sea or submergence of the land during
the glacial epoch. The Arctic shells and sea sand
on Moel Tryfaen, 1360 feet above the present sea
level, is one of the most striking of these evidences.
These shells, of no less than fifty-seven species of
mollusca, are deposited in a bed of sand and gravel
35 feet thick. From careful study of this deposit
Professor Ramsay “ estimated the probable amount
of submergence during some part of the glacial
period at about 2300 feet.” * The shells appear
to have been “ an accumulation in shallow water
or on a beach, and it probably acquired its
thickness during the gradual subsidence of the coast.” f
The neighbouring deposits indicate a further
subsidence of about 1000 feet, during which the shells
disappeared, and a colder climate followed. A
thin stratum of stiff clay overlies the whole. The
dying out of animal life with little or no change
in the inorganic portion of the deposit, and the
surrounding indications of subsequent glaciation,
all justify the conclusion that the shells belong to
an early stage of the glacial epoch, when the
climate was gradually changing from its previous
mildness ; and that the sea level gradually rose, or
* See Lyell’s ‘ Elements of Geology,’ p. 159, 6th edition.
f Ibid., p. 158.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
