148 TOWX GEOLOGY. [vi. 



upheaved to its present height above and out of the 

 lower lands around. But when he came to examine 

 sections, he would find his reasonable guess utterly 

 wrong. Snowdon is no swelling up of the earth's 

 crust. The beds do not, as they w^ould in that case, 

 slope up to it. They slope up from it, to the north- 

 west in one direction, and the south-south-west in the 

 other ; and Snowdon is a mere insignificant boss, left 

 hanging on one slope of what was once an enormous 

 trough, or valley, of strata far older than itself. By 

 restoring these strata, in the direction of the angles, 

 in which they crop out, and vanish at the surface, it is 

 found that to the north-west the direction of the 

 Menai Straits they must once have risen to a height 

 of at least six or seven thousand feet ; and more, by 

 restoring them, specially the ash-bed of Snowdon, 

 towards the south-east which can be done by the 

 guidance of certain patches of it left on other hills 

 it is found that south of Ffestiniog, where the Cambrian 

 rocks rise again to the surface, the south side of the 

 trough must have sloped upwards to a height of from 

 fifteen to twenty thousand feet, whether at the bottom 

 of the sea, or in the upper air, we cannot tell. But 

 the fact is certain, that off the surface of Wales, south 

 of Ffestiniog a mass of solid rock as high as the Andes 

 has been worn down and carried bodily away; and 

 that a few miles south again, the peak of Arran 

 Mowddy, which is now not two thousand feet high, was 

 once either under the sea or above it nearer ten 

 thousand feet. 



If I am asked whither is all that enormous mass 

 of rock millions of tons gone ? Where is it now ? 

 I know not. But if I dared to hazard a guess, I 



