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A 
a 
OLD RED SANDSTONE OF WESTERN EUROPE. 315 
These subdivisions will now be described in order, beginning with the 
lowest. 
1. Basement Conglomerate.—This rock is partially seen near the mouth 
of Ousedale Water, where it was observed by SEDGWwIcK and MuRcHISON. 
It does not rest there directly upon the granite, but is brought against it 
by a small fault which runs up the Ousedale valley, and strikes into the 
hills above Ousedale farm. As described by these writers, it there presents 
a remarkable granitoid aspect, insomuch that where the lines of stratifi- 
cation fail, and the texture of the rock is at its coarsest, neither in 
hand specimens nor in the sections of the cliff is it easy to determine where 
the conglomerate ends and the granite begins. A similar character is 
shown by the brecciated conglomerate of Badbea. It is on the Berriedale 
Water, however, that the relations of this lower conglomerate to the meta- 
morphic platform are best seen. That stream, as already mentioned, has cut 
through the eastern end of the Scarabin range, and in so doing has laid open 
a fine section of the conglomerate for nearly a mile along its junction with the 
older rocks not far below Braemore. Wrapping round the ends of the beds of 
coarsely foliated orthoclase gneiss above referred to, it dips gently away from 
the hills, and passes under the sandstones and shales of Group No. 2. Laid 
bare both in the bed of the stream and in the cliffs on either side, its position 
on an uneven surface of the older rock is made very clear. Its component. 
blocks vary in size up to as much asa yard, or even more, in length, and consist 
of gneiss, pink granite, quartz-porphyry, quartz-rock, mica-schist, and other 
crystalline rocks, with abundance of pink cleavable orthoclase derived from the 
underlying gneiss. They are for the most part tolerably well rounded, and in 
this respect, as well as in their larger size, they serve to mark this basement 
rock from the brecciated mass of Badbea. There is hardly any further trace of 
bedding than is sufficient to indicate that the rock inclines at a gentle angle 
against the gneiss, and dips under the sandstones. It is a coarse tumultuous 
shingle, such as might have been heaped up against a steep rocky shore, exposed 
to waves, driven by prevalent winds across a broad surface of water. In Old 
Red Sandstone times, the Scarabin ridge probably rose steeply from the 
southern margin of Lake Orcadie, which stretched thence northwards as far as 
the hills of Shetland—a distance of 140 miles. If in that ancient period the 
north-east wind blew with any approach to the fury with which it rushes along 
the cliffs at the present day, a sweep of 140 miles would be amply sufficient to 
raise waves capable of moving and rounding as coarse shingle as that which 
forms the basement conglomerate.* 
* When walking along the summits of the cliffs in Caithness and Orkney, I have often been struck 
by the evidence of the enormous force of the wind, which, caught in the clefts of these precipices, and 
converging upwards as in so many funnels, sweeps across the bald and barren ground at the top. 
