1823.] the principal Mounlain Chains of Europe. - 3 



nesian limestone. 4. The lias and oolitic series (Jura limestone 

 of the French). 5. Green sand. 6. Chalk. 7. Tertiary form- 

 ations reposing on the chalk. 8. Overlying trap and volcanic 

 districts. 



I shall proceed to give a hasty sketch of the general distribu- 

 tion of these formations, following the order above specified. 



1. Primitive and Transition Districts. 



So intimate is the connexion between the schistose rocks of 

 these two distinct seras (if distinct indeed they be, which some 

 recent geologists appear strongly inclined to question), that it is 

 impossible in any general map (unless the scale were such as to 

 admit a separate colour for each individual rock), to assign any 

 accurate line of division. In tracing, however, the tracts which 

 fall under this description, I shall, as far as materials are 

 afforded, and the nature of so general a sketch will admit, specify 

 the leading character of the constituent formations. 



Europe may be considered, when viewed under its most 

 general aspect, as presenting a vast central basin occupied by 

 the deposits of the secondary and tertiary class, surrounded by a 

 border of alpine chains, exhibiting the older rocks of which we 

 are now about to treat. 



This border, however, is not continuous, but interrupted by 

 openings, frequently very considerable, separating the constituent 

 chains. 



Neither is the included basin exclusively occupied by an unin- 

 terrupted series of the more recent deposits ; but mountain 

 groupes of the older rocks in places break through the mantle 

 thus thrown over them, and reappear towering above the 

 vicinity. 



On the south of the great bounding chains, e. g. in Spain, 

 Italy, &c. the same or similar secondary and tertiary deposits 

 are repeated, forming portions of another great basin which may 

 be designated as that of the Mediterranean. 



There are other smaller and local basins comprehended by the 

 tortuous course of the great chains. 



The chains and groupes of the primitive mountains appear to 

 present the centres of the greatest disturbances which have 

 uif'ected the surface of the earth, their strata being always ele- 

 vated under high angles, often indeed in vertical planes, and 

 exhibiting dislocations which can be referred to no cause but 

 mechanical violence. 



The extent of these disturbances appears often at least to be 

 in proportion to the height of the chain ; so that when the older 

 chains form very elevated mountains (as in the Alps and Pyre- 

 nees), the secondary strata, and even those of very recent 

 origin, are thrown into elevated planes, exhibit extraordinary 

 contortions, and themselves form lofty collateral mountain 

 rang< g; but where, as in England, the older chains are compa- 



b 2 



