Ch.XXVL] j 
IN CONTACT WITH GRANITE. 
371 
near the contact with the veins. These appearances are well 
seen at the junction of the granite and killas in St. Michael's 
Mount, a small island nearly 300 feet high, situated in the bay, 
at the distance of about three miles from Penzance. 
In the department of the Hautes Alpes, in France, near 
Vizille, M. Elie de Beaumont traced a black argillaceous 
limestone, charged with belemnites to within a few yards of a 
mass of granite. Here the limestone begins to put on a 
No. 90. 
Junction of granite with Jurassic or oolite strata in the Alps, near Champoieon. 
granular texture, but is extremely fine-grained. When nearer 
the junction it becomes grey and has a saccharoid structure. 
In another locality, near Champoieon, a granite composed of 
quartz, black mica, and rose-coloured felspar, is observed 
partly to overlie the secondary rocks, producing an alteration 
which extends for about thirty feet downwards, diminishing in 
the inferior beds which lie farthest from the granite. (See wood- 
cut No. 90.) In the altered mass the argillaceous beds are 
hardened, the limestone is saccharoid, the grits quartzose, and in 
the midst of them is a thin layer of an imperfect granite. It is 
also an important circumstance, that near the point of contact 
both the granite and the secondary rocks become metalliferous, 
and contain nests and small veins of blende, galena, iron, and 
copper pyrites. The stratified rocks become harder and more 
2 B 2 
