19S M . B R o N G N I A R T OH the position 



Article IV. 



Opinions of Geologists on the position of the Serpen- 

 tines and Diallage rocks. 



■ ■.or' 



1 have said that the greater part, and perhaps even all 

 geologists have entertaiued, and even published, on the 

 epoch of the occurrence of serpentine, an opinion which 

 appears to refer this rock to an epoch of formation much 

 more ancient thati the observations I have madfe bn the 

 Apennines appear to attribute to it. I shall not undertake 

 to bring forward their opinions, that would be to repeat 

 what is contained in the greater part of geological rocks ; 

 yet I cannot entirely pass them in silence, because some 

 light may result from an exiamination of these opinions, 

 which may lead us to a more precise distinction of the 

 diiferent serpentine rocks. 



It is known that the geologists of Werner's school distin- 

 guish, with this father of geognosy, two formations of ser- 

 pentine ; the one, according to them, belonging to the pri- 

 mitive class, contains noble serpentine, granular ophicalce 

 (ophicalce grenu), steachist, &c. and alternates with 

 Crystalline limestone, &c. ; the other, which they refer to 

 the last members or rocks of the primitive series, contains 

 common serpentine. 



All agree that the distinction of these two formations is 

 difficult to establish, artd consequently to recognise clearly. 

 Now, by refering the serpentine rocks of the Apennines, 

 which I have described, to the second formation, they are 

 seen to be in a position that attaches them to an epoch much 

 more recent than that of the last primitive rocks, or argil- 

 laceous transition slates. The opinion of the Italian geo- 

 logists and those who have spoken of the geology of the 

 Apennines, ought first and principally to occupy me. 

 Messrs Viviani and Corclier have visited the environs of 

 Rochetta, the mountain of Montenero to the E. of that vil- 

 lage, and the situations of the manganese, the umber earth, 

 the jasper, and diallage rock which it contains. 



