6 “-T & Hunt on Alpine Geology. 
These conclusions were not, however, admitted by Sismonda, 
who in 1866 presented to the Royal Academy of Sciences of Tu- 
rin an elaborate memoir on the anthracitic system of the Alps.* 
In this, while admitting at Petit-Coeur the existence of evidence 
of more or less contortion, rupture and over-riding (enchevauche- 
ment) of the strata, he still maintains that the anthracitic system 
of Maurienne and Tarentaise is one great continuous series 
of jurassic age, from the fundamental gneiss and protogine, 
upon which it immediately rests, to the upper member in whic 
ov 
occur thick beds of anthracite with an abundant carboniferous 
ora; which he assigns, however, to the middle oolite (Oxfor- 
dian) ; the great mass of strata below being referred to the lias. 
He then particularly indicated the line of the great Mont Cenis 
tunnel, which, commencing in the upper anthracitic member, 
should pass downward through the quartzites and gypsums, 
thence through talcose schists and limestones, as far as Bardon- 
necchia. These schists and limestones, according to him, are in 
‘‘a very advanced state of metamorphism,” and include eruptive 
ee (ey with euphotide, steatite and other magnesian rocks. 
(about fifteen miles to the southwest of Mont Cenis), a distance 
of 12,220 meters. The direction of the tunnel is N. 14° W., 
and the dip of the strata throughout nearly uniform, N. 55° W. 
at an angle of about 50°. From this we deduce by calculation 
that the vertical thickness of the strata is equal to nearly 60 
~ cent of the distance traversed, or in round numbers about 
000 meters. Of this not less than 5831 meters, beginning at the 
southern extremity, are occupied by the lustrous more or less 
talcose schists with crystalline micaceous limestones, often cut 
by veins of quartz with chlorite and calcite. Above there are 
515 meters in thickness of alternations of anhydrous sulphate 
nating with greenish talcose schists, and enclosing veins and 
. . _ 
of specimens above this, but for the distance of 1707 meters 
. from the northern entrance to the tunnel, corresponding to a 
vertical thickness of 1024 meters, we have principally sand- 
* Memoirs of the Acad., 2d series, xxiv, 333. 
sl oaeigiey et gee ar Aan Le a nk, tie Sr 
