M. E. SUESS EASTERN ALPS. 29 



question. Any geological map of Germany shows, at the first 

 aspect, that, northward of a line running from Passau, through 

 Ratisbonne, to Basel, the several Jurassic and Triassic series of 

 deposits {dtages) dip regularly with each other, appearing on the 

 map as concentric zones, the geological age of which becomes of 

 older date, and the contact of which with the older rock-massifs of 

 Central Europe becomes closer, in proportion to their progression in 

 the north-west direction. The same phsenomenon, although by far 

 more indistinct, may be observed as far as the south of Lyons. It 

 becomes very apparent again on the margin of the great Paris- and 

 London-basin, where it has been studied by Elie de Beaumont, Hebert, 

 and many other geologists. 



The diffusion of the "variegated sandstone" throughout these 

 regions indicates approximative^ the form of the land-areas at the 

 beginning of the secondary period. The most interesting among 

 them are the central plateau of France, the great continent east and 

 west of Coblenz, and the continent of Bohemia. Smaller islands, 

 between these three large continents, occur in the Rhenish countries 

 (Gresly's " Hercynian," " Vogesian," and "Bruchsal" Islands), 

 and are represented in the present Alpine chain (especially in the 

 Tyrolian portion) by deposits of littoral character. As the deposits 

 retrograde to the centre of the single basins, the separate islands of 

 this archipelago unite, sooner or later, into coherent masses. During 

 the close of the Jurassic period, a continuous tract of land extended 

 from Silesia to Namur ; and the inhabitants of the narrower and 

 scarcely connected seas of this epoch lose their uniformity of cha- 

 racter. The contrast between the Jurassic seas of Northern and 

 Southern Europe becomes more and more striking ; and the littoral 

 or subpelagic deposits in Wurttemberg and Bavaria, as they decrease 

 in geological antiquity, assimilate themselves more and more to the 

 pelagic deposits of the coeval seas in the Alpine region. 



The only explanation to be given of these phaenomena is a general 

 upheaval (although occasionally interrupted by oscillations) of the 

 whole secondary archipelago during an extremely protracted lapse of 

 time. This upheaval not only connected the single islands, and 

 brought them nearer the shore-line, but also imparted a more and 

 more littoral character to the strata deposited on the surface at 

 present occupied by the Alps. Under such circumstances, and 

 under the influence of the vast deposits already formed, the pelagic 

 character could not give way to another of more subpelagic aspect. 



Palseontological facts tend to confirm the induction, that (gene- 

 rally taken) the more recent an Alpine secondary deposit is, the 

 more it must agree with the secondary deposits of Franconia and 

 Suabia. Whilst nearly the whole of the Alpine trias is perfectly 

 different from the coeval deposits in the rest of Europe, the basis of 

 the Jurassic group shows a series of strata of generally a very pure 

 calcareous nature, and containing two or three littoral species, ex- 

 tending as far as Ireland. The number of concordant forms in- 

 creases in the Upper Lias, and they acquire a very considerable 

 share in the Upper Jurassic fauna. 



