562 MISS M. M. OGTLVIE [mRS. GOEDON] ON THE [Aug. 1 899, 



(2) It rests conformably upon successively higher and higher palaeon- 



tological zones of these thinly-bedded strata, when followed from 

 south and south-west to north and north-east through the heart of 

 that district. 



(3) Its upper limit, with reference to the succeeding Eaibl strata, varies at 



different localities ^ correspondingly, but more rapidly and somewhat 

 more irregularly; in no case, however, do Raibl strata repose upon 

 any other horizon than Schlern Dolomite. 



(4) Fragmentary tufaceous material, associated with contemporaneous 



eruptive activity, is intermixed with all the thinly-bedded earthy 

 series — Wengen, Cassian, and E-aibl strata. 



(5) Intersti-atified with the tufaceous deposits are lenticular beds, blocks, 



and thinly-spread banks (Oipit-Kalk) of coral-growth, both in 

 Cassian and Raibl strata ; on the other hand, such coral-growths were 

 observed to be comparatively rare in the Schlern Dolomite itself. 

 This was found to be a stratified marine deposit, in which 

 remains of algal, mollusoan, and echinoderm life (even if so much 

 altered by dolomitization as merely to deserve the name of ' traces ') 

 prevailed far more largely than corals. 



(6) The heteropism exhibited in the lithological facies presented by the 



palseontological zones of Wengen and Cassian strata led me to the 

 conclusion that an ancient geographical limiting-line (now localh' 

 segmented) had extended in Triassic time east and west through the 

 Dolomite-region. To the south of this line the earthy Wengen and 

 Cassian strata disappear, giving place to thick masses of calcareous 

 rock, namely, the Marmolata-Kalk ; hence I concluded that the 

 Schlern Dolomite of Groden, etc. was the time-equivalent of the 

 higher horizons of the calcareous Marmolata-facies to the south, 

 while the earthy Wengen-Cassian strata represent in time the lower 

 horizons of the southern calcareous series. 



Having traced segments of the old geographical limit of Cassian 

 and Wengen time along the exposures of igneous and tufaceous 

 rock, from Mahlknecht through Duron, E-odella, Sasso di Mezzodi, 

 etc., to Col di Lana, I explained the existence of such a limit as 

 the result of a downthrow to the south during the time of deposition 

 of the different Middle-Triassic facies ; and stated that, in my 

 opinion, ' contemporaneous faulting and volcanic action were the 

 cause of mid-Triassic heteropism in South Tyrol.' ^ 



These conclusions show distinctly that such palseontological and 

 lithological evidence as is obtainable does not support the application 

 of Darwin's theory of the origin of coral-reefs which had been 

 made to this particular region of the Alps. 



Tectonic. — The brilliant researches and conclusions of Mojsi- 

 sovics, Sness, Vacek, Benecke, Bittner, and others respecting the 

 complicated structure and tectonic accidents of the Peri-Adriatic 

 region are familiar to students of Alpine geology. So long as little 

 was known of the extraordinary effects of earth-crust movement in 

 mountain-ranges, it was but natural that geologists should regard 

 the peculiar forms of the Dolomite-massives in the Tyrol as original 

 structures. But, with the growth of our knowledge of" the compli- 

 cated structures of mountain-regions during the last quarter of a 



^ S. von Wohrmann & Koken, ' Die Fauna der Eaibler Schichten vom 

 Schlernplateau,' Zeitschr. d. Deatsch. geol. G-esellsch. vol. xliv (1892) p. 167. 

 ^ Geol. Mag. 1894, p. 10. 



