Sketch of a Classification of the European Rocks. 33 



introduced into beds contemporaneous either with the oolite series or 

 the greensand." Now when such important changes as those no- 

 ticed by my friend M. Elie de Beaumont can be fairly traced, what 

 may we not expect to find in the sequel, when geologists shall cease 

 to be contented with referring a particular mineralogical structure to 

 the old divisions transition and primitive, of which the former seems 

 only to have been created as a geological trap. 



Unstbatified Rocks. — This great natural division is one of 

 considerable importance in the history of our globe. To the rocks 

 composing it, and the forces which threw them up, may be attributed 

 the dislocations and fractures in the stratified rocks every where so 

 common, and in many instances their elevations into lofty mountain 

 ranges. In many of the great chains the trap rocks are visible along 

 tlieir line of elevation, as was first observed by M. Von Buch in the 

 Alps, — on the southern side of which they are exposed at intervals ; 

 and it is on this side that there is so much dolomite in the limestones. 

 To assert that igneous rocks cannot be present along the whole of 

 this line because not every where visible on this surface, is like af- 

 firming that there is no table beneath a cloth spread on it except in 

 the cases where there may be a few holes. We are too apt in judg- 

 ing of the mass and thickness of rocks to compare them with our own 

 size, and imagine them enormous, expressing surprise at the immense 

 forces which it must have required to raise such masses into moun- 

 tains ; when if they were compared, as they ought to be, with the 

 mass of the world, the thickness becomes trifling, the highest moun- 

 tains insignificant, and the forces required to raise them comparatively 

 small. 



That granitic, trappean, and serpentinous rocks have exercised 

 a great influence on the present position of the stratified rocks, few 

 geologists will doubt. The igneous origin of the two former is also 

 very generally admitted ; but though the third is not so generally re- 

 ferred to that origin, I know not how we can deny that it was pro- 

 duced by a cause somewhat similar to that which produced the oth- 

 ers, when we consider its mode of occurrence, more particularly in 

 the Alps and in Italy. 



The geological dates of the elevations of mountains is a most im- 

 portant subject, and one on which M. Elie de Beaumont read a very 

 interesting paper, in June last, before the Institute of France.* His 



" The first part of this paper has been published in the Aniiales des Sciences JVat- 

 ■urelles for September. 



