im St. Michael’s Mount in Cornwall. 437 
sides, has a vein of quartz an inch thick, gray at ifs con- 
tact with the granite, and brownish towards the middle.— 
A third mass, still with granife on sip sides, contains a 
vein of white quartz confusedly ervstallized.—In a- fourth 
mass, the capels of quartz have their surface covered with 
smal] crystals, against which, on each side, has been formed 
a stratum of quartz confusedly crystallized —Lastly, a fifth 
specimen, the vein of which is an inch and half in breadth, 
has the true character of mineral veins, that of symmetricat 
deposites on both sides of the fissures. Similar coatings of 
white quartz have advanced on both sides’; but not having 
every where united in the middle, they are covered in the 
intervals with small crystals. 
if Mr. Ailan had seen my own work, be would not have 
thought I was mistaken; since I have not only described 
myself the very phenomena that he opposes to me as ob- 
served in the specimen which he laid before the Edinburgh 
Society, but this is only a very small part of the seological 
circumstances which I have described in that country. “The 
principal of them, against the Huttonian system, were: 
the stratification of granite ; the broken and shattered state 
of its sirata, no less than those of kelias by the same cause 
that of the subsidence of part of them ; and the evidence of 
the veins of St. Michael’s Mount having all the character 
of mineral veins, on which the Hattonian. system had spread 
many errors: an object to which I shall particularly come, 
after having mentioned my last publication of two volumes 
of Travels in some Parts of Switzerland, France, and Ger- 
many. 
One of the objects which is there completely elucidated 
is the stratification of granite, exemplified in some moun- 
tains of Upper Lusatia, called the Giant’s Mountains. 
These [ have described, not only a very extensive and high 
ridge composed of granile strata, and their contemporary 
of gneiss, with the strongest characters of dislocation ; but 
many mounts on the outside of the chain formed of the 
same strata, visibly by subsidence. Aud besides, 1 have 
described, in the whole course of these Travels, instances of 
the great phenomenon of enormous blocks of granite and 
other contemporary substances. Mr. Playfair supposed, 
as I have already mentioned, that they had been propelled by 
the streams descending fron’ the mountains; but I have 
described, ina great many places, heaps of them on very 
high hills, and for insianee over the high ridge of Mount 
Jura. — But this subject is sufficiently elucidated, and I 
come to that of the mineral veins. 
Ee3 The 
