i-tS Mr. De la Beclie's Sketch of a Classification 



one and the other of these rocks contain a considerable num- 

 ber of belemnites transformed into white calcareous spar, but 

 of which the general forms and alveoli are nevertlieless very 

 visible, and can leave no doubt as to the nature of the fossils. 

 As these limestone beds are the prolongation of those in which 

 the trypsum of the Val Canaria is found, and as these are the 

 same With those in which the dolomite of Campo Longo oc- 

 curs, we can assure ourselves that all the curious luineralogical 

 phtenomena of the St. Gothard have been introduced into beds 

 contemporaneous either with the oolite series or the green- 

 sand." Now when such important changes as those noticed 

 by niy 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. 



Unstratified 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 strati- 

 fied rocks every where so common, and in many instances 

 their elevations into lofty mountain ranges. In many of the 

 oreat chains the trap rocks are visible along their line of ele- 

 vation, 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 lime- 

 stones. To assert that igneous rocks cannot be present along 

 the whole of this line because not every where visible on the 

 surface, is like affirming that there is no table beneath a cloth 

 spread on it exce})t in the cases where there may be a few 

 holes. We are too apt in judging 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 mountains ; 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 com- 

 paratively small. 



That granitic, trappean, and serpentinous rocks have exer- 

 cised a o-reat 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 thougli the 

 third is not so generally referred to that origin, I know not 

 how we can deny that it was produced by a cause somewhat 



similar 



