PLUTONIC BOOKS OF OOLITE AND LIAS. 
571 
Fiof. 619. 
posed by denudation, at the height of 2000 or 3000 feet on 
the flanks of that chain. 
Plutonic Rocks of the Oolite and Lias. —In the Department 
of the Hautes Alpes, in France, 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 granular texture, but is extremely fine¬ 
grained. When nearer the junction it becomes gray, and 
has a saccharoid structure. In another locality, near Cham- 
poleon, a granite composed of quartz, black mica, and rose- 
colored feldspar is'ob¬ 
served partly to overlie 
the secondary rocks, 
producing an altera¬ 
tion which extends for 
about 30 feet down¬ 
ward, diminishing in 
the beds which lie 
farthest from the gran¬ 
ite. (See Fig. 619.) In 
the altered mass the . 
argillaceous beds are 
hardened, the lime¬ 
stone is saccharoid, the 
grits quartzose, and in 
the midst of them is a 
thin layer of an imper¬ 
fect granite. It is also junction of granite with Jurassic or Oolite strata in 
an important circuni- the Alps, near Champoleon. 
stance 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 crystalline, but the 
granite, on the contrary, softer and less perfectly crystallized 
near the junction.* Although the granite is incumbent in 
the above section (Fig. 619), we can not assume that it over¬ 
flowed the strata, for the disturbances of the rocks are so 
great in this part of the Alps that their original position is 
often inverted. 
At Predazzo, in the Tyrol, secondary strata, some of which 
are limestones of the Oolitic period, have been traversed and 
altered by plutonic rocks, one portion of which is an augitic 
porphyry, which passes insensibly into granite. The lime- 
* Elie de Beanmont, sur les Montagnes de I’Oisans, etc. Mem. de la Soc. 
dTlist. Nat. de Paris, tom. v. 
