200 THE OLD RED SANDSTONE. 
been dug out of the slope by the slow wear of the waves, in 
the unreckoned course of that period during which the 
present sea was bounded in this locality by the existing line 
of coast. (See Frontispiece, sect. 3.) 
I know nota more instructive walk for the young geologist 
than that furnished by the two miles of shore along which this 
section extends. Years of examination and inquiry would 
fail to exhaust it. It presents us, I have said, with the numer- 
ous organisms of the Lower Old Red Sandstone ; it presents 
us also, towards its western extremity, with the still more 
numerous organisms of the Lower and Upper Lias; nor are 
the inflections and faults which its strata exhibit less instruc- 
tive than its fossils or its vast denuded hollow. I have climbed 
along its wall of cliffs during the height of a tempestuous 
winter tide, when waves of huge volume, that had begun to 
gather strength under the night of the Northern Ocean, were 
bursting and foaming below; and as the harder pebbles, up- 
lifted by the surge, rolled by thousands and tens of thousands 
along the rocky bettom, and the work of denudation went on, 
I have thought of the remote past, when the same agents had 
first begun to grind down the upper strata, whose broken edges 
now projected high over my head on the one hand, and lay 
buried far under the waves at my feet on the other. Almost 
all mountain chains present their abrupter escarpements to the 
sea, though separated from it in many instances by hundreds 
of miles —a consequence, it is probable, of a similar course 
of denudation, ere they had attained their present altitude, or 
the plains at their feet had been elevated over the level of 
the ocean. Had a rise of a hundred feet taken place in this 
northern district in the days of Cesar, the whole upper part 
of the Moray Frith would have been laid dry, and it would 
now have seemed as inexplicable that this roof-like ridge 
