204 M. BnoNGNiAUT on the position 



that case it is granular limestone, to the primordial rocks, 

 and the second more compact, &c. to the last periods of that 

 formation ; he also cites the serpentines and diallage rocks 

 of the Apennines, as dipping beneath the most ancient inter- 

 mediate rocks. He premises that there exists much uncer- 

 tainty and obscurity on the position of the two serpentine 

 formations. 



There apparently results from the facts and resemblances 

 presented in this memoir : 



1st. A tolerably exact knowledge of the relations of the 

 serpentiae and diallage rock with the jasper. 



2dly. A precise determination of the rocks on which the 

 preceding are immediately placed. 



3dly. Numerous and authentic examples of the existence 

 of serpentine and jasper rocks above a limestone of sedi- 

 ment, and above sandy and micaceous rocks of aggregation. 



4thly. Direct proofs that the serpentine rocks of Ro- 

 chetta, la Spezia, of Prato, of Pietramala, of Imprunetta, of 

 the Volterranais, ought to be regarded as of posterior forma- 

 mation to the rocks of sediment and aggregation, and strong 

 presumptions, drawn from analogy, that the serpentine 

 rocks of la Guardia, of Monte-Ramazzo, of the Bocchetta, 

 &c. in the Apennines ; of Musinet, Baldissero, and Castel- 

 lamonte, at the foot of the Alps, and that even the rocks of 

 serpentine greenstone (diabase ophiteux) of the Pyrenees, ■ 

 ought to be referred to this same formation. 



5thly. Lastly, that rocks analogous to granites by their 

 crystalline structure, again spreading over the surface of the 

 globe after the existence of organic bodies, have covered 

 rocks of sediment and aggregation containing the debris of 

 these bodies. 



This fact occurring with the same circumstances in very 

 distant places, there is reason for believing that it has been 

 as general as the most part of geological phenomena re- 

 lating to the regular succession and sensible parallelism of 

 the beds of the globe. 



