Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/367

 must have been, on this supposition, produced by a mass of water greater than that which caused these, and we can have no reason for supposing that flow attended by a less velocity. That three currents so different in depth should have been propelled with momenta capable of producing effects so equal, is in itself a supposition considerably improbable; but among the other more obvious difficulties attending this explanation it is unnecessary to dwell on this in particular.

The form, dimension and equality visible throughout the whole, present additional obstacles to the supposition that a deluge was the cause of these lines. Among the numerous difficulties which occur in attempting to solve their formation on this view, it is perhaps a trifling one, that three successive torrents should produce three deposits of alluvial matter, of which the sections should be so generally equal and similar: there are many of a more serious nature. I have shown that the deposits in the upper part of the glen in which the lines are traced, are of sharp materials mixed with fine clay, while at its lower part they consist of rounded matter mixed with sand and gravel. If the deposit which occupies the glen had consisted of foreign substances introduced by the flow of a torrent, it should have been formed of rounded matter throughout: in any case there should have been a similarity between the two. Nor is there any reason why it should not be equally found on hard and rocky ground as on a soft surface, since the forms and inclinations of the hills are so often alike.

It is an objection still more serious to this hypothesis, that the thickness and disposition of the alluvia should not be affected by the angular direction of the valley, and by the deviations from a direct line to which it is subject. If we conceive a current flowing through a channel of a bent or zigzag form, it is obvious that its