Proceedings of the Geological Society of France. 155 



stages of creation, existed in an uncombined condition, — that, after- 

 wards, they had united and evolved much heat, — that the crust of 

 the earth x'esulted from the cooling of the surface, and that this cool- 

 ing process is still incomplete at a short distance within its interior. 

 By others it is conceived that in some remote period of time the 

 earth had passed through a highly-heated region of space, or of space 

 occupied by some ether or other medium intensely hot ; and that the 

 internal heat of the earth is the remains of the heat then acquired 

 by it, — the surface having cooled and hardened as before. If either 

 of these views, or indeed, so far as I am aware, any of the others 

 upon the subject be received, it will be obvious, that the heat exist- 

 ing in the interior of the globe may be represented as a temporary 

 and decaying power, inasmuch as it has no element of perpetuity and 

 restoration within itself. It has a tendency in the course of time to 

 arrire at rest and equilibrium, and possesses nothing within itself to 

 break or counteract that rest, and so maintain itself in permanent 

 action. It is the remains of an excitation of force and motion, which 

 took place in some distant poi'iod of time, and the cause of which is 

 unknown to us, and has ceased to operate. Such being the case, 

 therefore, the consideration of these motions hardly comes under our 

 pi'esent subject, which refers to the origin of the motions belonging 

 to the present order of things. 



( To he concluded in next Ntcmber.) 



Account of the Proceedings of the Geological Society of France 

 for 1847. By Sir Henry de la Beche, President of the 

 Geological Society of London. 



In a connnunication on the variations of the igneous rocks, M. Du- 

 rocher points out many examples of change, such as the passage of 

 greenstone (diorite) into diallage rock and serpentine in the C6tes-du- 

 Nord and the Loire Inferieure, and in other places in Brittany into 

 syenite. lie also mentions, that they sometimes present the appear- 

 ance of quartziferous porphyry and petrosilex, and not only pass 

 into diallage rock, but like serpentine contain oxidulated iron, as in 

 Scandinavia. After citing various other examples, such as the pas- 

 sage in Norway of granite into the syenite, in which so many rare 

 minerals are discovered, M. Durocher remarks, that the variations 

 are not so extraordinary as they appear, these igneous rocks contain- 

 ing the same elements, — silica, alumina, potash, soda, lime, magnesia, 

 and oxide of iron ; granite being the most rich in silica and alumina, 

 the poorest in lime, magnesia, and oxide of iron. When a granite 

 becomes hornblendic and passes into syenite, the proportion of lime 

 and oxide of iron augments, while that of alumina and potash or 



