in St. Michael’s Mount in Cornwall. 435 
The whole of my description of the peninsula of Corn- 
wall, had Mr. Allan known it, would have convinced him 
that I was not the inattentive observer he considered me to 
be: but I confine myself to the above particulars concerning 
the stratification of granite which is here my object; and 
T return to the part of Cornwall on the road from the gulf 
of Padstow, on the north side, to that of Mount’s Bay on 
the south. 
From p. 188 of the same volume, I describe a bill near 
St. Columb, where quarries were open, which at first sight, 
and not observing the nature of the stone, would certainly 
have been taken for lime-stone or sand-stone quarries, so 
regular were the strata, of which were taken stones for 
building the fronts of houses. These sérata are much i- 
clined, and they are lost, on one side, under a thick loose 
soil; while on the other side they present their upper 
section toward the surface; a proof that their inclined and 
broken state has been owing to the catastrophes common 
to all the strata. 
But another circumstance of that hill will further prove 
the error of Mr. Playfair on the cause of one of the greatest 
geological phenomena, the great dissemination of blocks 
of granite on countries far from every mountain of their 
kind. Mr. Playfair supposed that these masses had been 
propelled by the streams descending from the mountains ; 
and he thought that they might be traced up to their 
source, by following their tract. But I have shown the 
illusion of this idea, by describing vast heaps of those llocks 
in plains at great distances from every mountain and large 
stream. I have also proved, by a great number of facts, 
that these masses must have been thrown up in the very 
places where they are found, by the explosion of the air 
compressed in the caverns in which sunk the parts of the 
strata that have disappeared outwards. 
Now there is a remarkable circumstance on a hill near 
St. Columb, described in p.194. After having observed the 
quarries, I walked some way up the hill: it is every where 
smooth and covered with turf, on which I saw a quantity 
of blocks of granite, but different from that of the quarries. 
The quarryman informed me, that these blocks were the only 
granite known on that bill, and bad been many years the 
object of his pursuit, till accidentally he discovered the 
strata by sounding through the turf with an iron bar, in 
order to discover more blocks near the cart road, as he had 
exhausted all those that were visible on the surface. He 
Ees still 
