336 RAMBLES OF A GEOLOGIST. 



thyolitic member of the Old Red ; but where the banks con- 

 tract, we find only its lowest member, the Great Conglomerate. 

 This last is by far the most picturesque member of the sys- 

 tem, abrupt and bold of outline in its hills, and mural in 

 its precipices. And nowhere does it exhibit a wilder or more 

 characteristic beauty than at the tall narrow portal of the 

 Auldgrande, where the river, after wailing for miles in a pent- 

 up channel, narrow as one of the lanes of old Edinburgh, and 

 hemmed in by walls quite as perpendicular, and nearly twice 

 as lofty, suddenly expands, first into a deep brown pool, and 

 then into a broad tumbling stream, that, as if permanently 

 affected in temper by the strict severity of the discipline to 

 which its early life had been subjected, frets and chafes in 

 all its after course, till it loses itself in the sea. The banks, 

 ere we reach the opening of the chasm, have become steep, 

 and wild, and densely wooded ; and there stand out on either 

 hand, giant crags, that plant their iron feet in the stream ; 

 here girdled with belts of rank succulent shrubs, that love the 

 damp shade and the frequent drizzle of the spray ; and there 

 hollow and bare, with their round pebbles sticking out from 

 the partially decomposed surface, like the piled-up skulls in the 

 great underground cemetery of the Parisians. Massy trees, 

 with their green fantastic roots rising high over the scanty 

 soil, and forming many a labyrinthine recess for the frog, the 

 toad, and the newt, stretch forth their gnarled arms athwart 

 the stream. In front of the opening, with but a black deep 

 pool between, there lies a mid-way bank of huge stones. Of 

 these, not a few of the more angular masses still bear, though 

 sorely worn by the torrent, the mark of the blasting iron, and 

 were evidently tumbled into the chasm from the fields above. 

 But in the chasm there was no rest for them, and so the arrowy 

 rush of the water in the confined channel swept them down, 

 till they dropped where they now lie, just where the widen- 

 ing bottom first served to dissipate the force of the current. 



