Three
of from five to seven tons' weight are spoken of as carried half a
mile, and one of probably twenty tons is seen about a quarter of a
mile below the place whence it evidently has been torn. These are
prodigies to the rustic population, little accustomed to think of the
dynamics of water, and totally ignorant of the deduction made in such
circumstances from the specific gravity of any heavy mass carried by
it. Geologists, who have looked into the great question of erratic
blocks, are less apt to be startled by such phenomena.
Some of these gentlemen will, I suspect, find the transport of blocks
at Holmfirth less remarkable than they could have desired. It is well
known that, while most of them ascribe the travelling of boulders to
the working of ice in former times, one or two persist in thinking
that water may have done it all. The present president of the
Geological Society has endeavoured to shew, by mathematical reasonings
chiefly, that the blocks of Shap Fell granite, scattered to the south
and east in Yorkshire, may have been carried there by a retreating
wave, on the mountain being suddenly raised out of the sea. Now here
is a moving flood, of greater force than any retreating wave could
well be; and yet we see that it does not carry similar blocks a
hundredth part of the way to which those masses of Shap Fell have been
transported, even although their course was all downwards moreover--a
different case from that of many of the Shap boulders, which are found
to have breasted considerable heights before resting where they now
are.
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