338 J. If. J add— On Vokanos. 



must bear in mind that of the periods which in surrounding districts 

 are totally unrepresented by sedimentary deposits (indicating that 

 these areas were not, during the periods in question, subjected to 

 depression, but rather, as shown by numerous and marked uncon- 

 formities, were the scenes of elevation and denudation) we find in 

 the same Alpine regions most important and interesting representa- 

 tives. Thus the Trias, which over so large a part of Northern 

 Europe exhibits evidences only cf the prevalence of terrestrial and 

 lacustrine conditions, is represented in the Alps by an enormous 

 thickness of strata, crowded with the- forms of marine life of the 

 period. The Ehsetic, which finds so inadequate a development in 

 other parts of Europe, is in the Alps a grand formation several thou- 

 sands of feet in thickness, which completely bridges over the interval 

 between the Triassic and Jurassic. Similarly, the great break which 

 in other areas exists between the Jurassic and Neocomian, and is so 

 often marked by strong unconformity, or the prevalence of land 

 surfaces and lacustrine deposits, does not exist in Alpine regions ; 

 but on the contrary a formation, not unfrequently thousands of feet 

 in thickness, and yielding an interesting fauna of intermediate 

 character, links the two together; so that the transitions from Jurassic 

 to Tithoniai), and from Tithonian to Neocomian, are alike imper- 

 ceptible. Even the very general unconformity at the base of the 

 Cretaceous finds no place in some parts of the Alpine area, for highly 

 fossiliferous deposits unite the highest members of the Neocomian 

 with the oldest beds of the Cretaceous. Lastly, even the greatest 

 gap of all, that between the Mesozoic and Tertiary deposits, is found 

 to be bridged over in the Alps ; and in the midst of the thick masses 

 of the Vienna and Carpathian sandstones it is impossible to draw 

 lines that may serve to divide these elsewhere distinctly separated 

 periods. Jn short, in the Alpine districts we seem to have clear 

 proof that from the commencement of the Triassic to the close of the 

 Nummulitic period continual subsidence, attended by constant depo- 

 sition, was going on, and that the interruptions or reversals of tliis 

 movement were only local and partial, and unattended with any 

 wide-spread effects. 



Still another confirmation of the same series of movements may 

 be found in the diversities between the faunas of the North and 

 South of Europe during the Mesozoic periods, — diversities which are 

 incapable of being accounted for by any difi'erences in climatal con- 

 ditions. While on the one hand it is demonstrable that no ridge 

 of land existed which during these periods served to separate these 

 distinctly marked life-provinces, we may point out the same effect 

 would have been produced by the presence of a great and constantly 

 depressed or deep-water area, such as we know existed during the 

 whole of these epochs in the Alpine region. 



As shown by Mr. Darwin, the existing areas of depression within 

 the tropical and sub-tropical portions of the earth's surface are often 

 marked b^^ the growth of coral-reefs ; and that the same was the 

 case during the long periods of subsidence of the Alpine regions is 

 clearly proved by the studies of Richthofen, Mojsissovics, and 



