DESCRCPTION OF SfOWlrt? MEZIN. SI I 



selves equally in the lowest anfl in the highest parts of the 

 mountains. Saussufre hud supposed this gypsum to be su- 

 perposed, but I easily satisfied myself, that it is in reality 

 intercalated. 



I have revisited almost all the extinct volcanoes in the in- Extinct volca. 

 ttrioi- of France. ,My object was to verify many of tny de- noe3 in France. 

 scrip»ions, and to make new ones, wherever 1 could find si- 

 tuations truly classicTil, that is, capable of being cited as 

 exhibitiuii a complete and perfectly circumscribed geologi- 

 cal phenomenon. 



1 have paid much attention to Mezin, which is a volcanic Mount Mezin. 



system aualoojous to P.uy-de-Dorne and Mont-d'Or,' but 



much better characterized. We see there two orders of vol- Two ordeis of 



canic substances'; those that were anterior to the last period ^o^^^^"'*^ s"^' 



. ■ stances, 



of deluge, and those that have been thrown out subsequent 



to all the revu^uhous the Earth has undi rgone. The mass The mountain 

 of the mountains is composed almost wholly of primitive ^-^"^'^'^^* 

 formations. Cons-idered as a whole, it is a frustum of a 

 very obtuse cone often leagues radius. I find, with Mr. 

 Ramond, that it is 1774 met. [1939 yds] above the level of 

 the sea, and about 800 met. [874 yds] above the granitic 

 flat on which it rests. It exhibits the ruins of a volcanic co- 

 lossus, unquestionably much loftier and more extensive. 

 W« find in it this very remarkable peculiarity, that most of The volcanic 



the incoherent matters thrown out have underojone no alte- substances un- 



. , ^ changed, 



ration, and have not been changed either into tnfs or brec- 

 cias. The red scoiae in fragments, and the black stonj- 

 scoriae, appear with all the characters impressed on them 

 by the fire. Add to this, all the currents, or segments of 

 currents, are accompanied with scorified crusts above and 

 below. The interior of these currents presents only lithoid 

 lavas, from the basaltic porphyry to the compact earthv, or 

 fine-grained granular porphyry with base of felcspar. The 

 tkree varieties with base of feldspar are frequently found in 

 the same current, and thus exhibit the transition of the Transition, 

 thr^e pretended species, domit, the base of graystone, and 

 clinkstone. 



The modern lavas are not very numerous at Mezin. They The later 

 are all formed of porphyritic basaltes witii fine crystals of *^' 

 peridot, and pyroxene, mixed with nodules of granular 



peridot. 



