52 Miss M. M. OgiMe — Coral in the "Dolomites." 



Here we see an easy loophole of misconception in working out the 

 stratigraphy of this area. How frequently it has given rise to error 

 becomes apparent on comparing the maps or sections of different 

 authors who have surveyed in the district ! 



An impression will now have been gathered of my opinion with 

 regard to heteropism in the "Dolomites." Beyond doubt that exists, 

 and to a very large extent; it alone explains the succession of Triassic 

 rock in the " Dolomites." There are also reef-like communities of 

 Corals, and of other fossil organisms, changing with the actual depth 

 of the water and the character of the surrounding sediment. The 

 Corals have but their fair sliare, along with other groups of marine 

 life, in the thickness of any one formation, and just as important as 

 the organic causes of heteropism are the inorganic. Most of all, 

 the clear presentation of two epochs is necessary — the one is the 

 volcanic period of Wengen age, when so many inequalities were 

 introduced into the relief of the sea-floor and diiferential movements 

 were set up in the basin of that part of the South Tyrol Triassic 

 sea ; the other is the Kaibl period, and what it tells us of the culmin- 

 ating point in an age of unequal deposits and especially fluctuating 

 conditions of level over these " volcanic " areas. 



IV.— Apparent "Reef-Formations" in the " Dolomites " largely result 

 from the particular history of Earth-movements in that area — 

 Occurrence of Vertical and Inclined Planes of Fault in the 

 " Dolomites " — Overthrusts— " Overcast " Bedding— Eflects of 

 Weathering. 



Gradually the waters of the Eh^tic and the great Jurassic ocean 

 advanced over Alpine areas and the deposits of the Triassic Ax-chi- 

 pelago lay sleeping at unknown depths below a heavy weight of 

 marine accumulations. The South Tyrol Trias and younger deposits 

 alike shared in the tektonic movements which passed over the Alps 

 during the long geological "days" of Mesozoic and early Tertiary 

 time ; but probably it was not until the Tertiary mountain-making 

 period that the series of deposits was affected by tearing or sliding 

 movements. 



Tertiary movement begins a much more difficult chapter in the 

 past history of the South Tyrol dolomites than the period of Triassic 

 deposition. And we might be content to omit it entirely from present 

 consideration, were it not that it produced many results in South 

 Tyrol which cannot be dissociated from the "Coral Eeef" question. 

 It has left its symbols indelibly written on the rocks of the 

 country, symbols as strange and as impossible of interpretation for 

 the early school of geologists as ever were the ancient characters 

 on the colossal monuments of Egypt and Syria for the unpractised 

 eye. And when we learn to read, one of the first Miocene symbols 

 in the "Dolomite" spells "Beef" and is, being translated, redupli- 

 cation and faulting of roclcs. 



The presence of a great number of vertical faults within the areas of 

 Enneberg and Ampezzo has been already proved, also the influence 

 of those In complicating the geology of the district and producing 



