462 Prof, Buckland on the Structure of the AIpSj [J'uNi, 



In the Pyrenees also we find the same limestones forming the 

 most elevated rid^e and great water shed of that vast chain, and 

 rising in Mount Perdu to 10578 feet, and in the Torre de Mar- 

 bore to 10;2()0. 



These alpine limestones include nearly all the calcareous for- 

 mations of England, from the magnesian limestone which lies 

 next above our coal measures upwards to chalk, piled on each 

 other without any subdividing strata of clay or sand, and all 

 assuming the common character of a comj)act grey marble, pos- 

 sessing no variations by which one part of the formation can be 

 distinguished from another. And such is generally the feature- 

 less condition of the great calcareous masses, which, extending 

 from the Pyrenees through the south of France by Avignon to 

 Dauphine, stretch thence uninterruptedly through Switzerland, 

 Tyrol, Saltzburg, and Styria, to the Danube below Vienna; 

 while on the south side of the central Alps a similar calcareous 

 mass extends from the Lago Maggiore and Como through the 

 Italian Tyrol into Croatia and Dalmatia. 



Fortunately this want of distinguishing feature is not universal; 

 occasionally spots occur in which the strata present evidences 

 which identify them with those of England, and throw light on 

 the history ot the 'arger and less distinctly characterized masses 

 of which they form a part. 



The general structure of the Alps and Jura mountains, and 

 the valleys adjacent, reduced to their most simple form, may be 

 briefly stated thus : 



1. General Structure of the great Alpine Chain, 



The central axis of this vast chain extending continuously 

 north eastward from Savoy through Switzerland, Tyrol, and 

 Styria, to Presburg, is composed of primitive rocks, the average 

 breadth of which is about 60 miles. In contact with these are 

 extensive masses of transition rocks, but their presence is irregu- 

 lar; and when they occur, there is nothing in the external features 

 of the country to mark their junction with the primitive masses. 



This central ridge of primitive and transition rocks is bounded 

 on each side by two vast belts of alpine limestone, coextensive 

 with, and continuous beyond the primitive chain. The elevation 

 of the latter sinks gradually as it advances north eastward, till^. 

 near Presburg, it drops below the bed of the Danube, and on the 

 north of that river again gradually rises to form the chain of the 

 Weise Gebirge which connects the Alps with the Carpathians. 



The lateral belts of alpine limestone maintain their elevation 

 more constantly than the primitive chain, and extend themselves 

 far beyond it ; the north belt stretching north-westwards from 

 Dauphine into Languedoc, and to the Pyrenees, and the south 

 belt south-eastward by C^irniola into Dalmatia. . 



These lateral belts are divisible into two systems, the elder 

 and younger alpine limestones ; the former contemporaneous 



