10 Miss M. M. Ogilvie — Coral m the '' Dolomites.'" 



2. The Coral remains occur sometimes in isolated blocks, sometimes in large 

 clumps of rock perforated by Thecosmilia species of Coral, and often full of fragments 

 of Echinoderms. These blocks or clumps occur in the midst of fine volcanic 

 mud, or the calcareous and dolomitic matter of the contemporaneous marine sediment, 

 and form more or less continuous beds with lenticular reef-like expansions. The 

 name they go by is " Cipit Limestones,''^ and they vary from 10 feet to 150 feet in. 

 thickness. 



3. "Cipit Limestones" are of episodal occurrence throughout the mid-Triassic 

 era, appearing at entirely irregular horizons of all Triassic strata between the 

 Muschelkalk and Dachstein dolomite. At the same time, in the ai-ea under dis- 

 cussion, there is one horizon pre-eminent for the interbedding of Cipit Limestones, 

 that is, the Cassian. 



4. In its lithological character and faunal distribution, the "Wengen and Cassian 

 period shows marked heteropism. While in deeper seas algse grew and Mollusca 

 prevailed, there was, not far from the island coasts of the mid-Alpine core of rocks, 

 a zone of submarine volcanic eruptiim. Lavas and ashes were swept intermittently 

 over the sea-floor. Along the hem of this volcanic girdle communities of Corals 

 and Echinoderms settled and formed a series of small barrier reefs (Cipit 

 Limestones), frequently interrupted in their growth by fresh lavas. On the outer, 

 seaward side, marine deposits continued to increase in thickness over a sinking 

 basin ; on its inner side, at first only a few mud-loving species of Halobia, Fosidono- 

 mya, etc., could exist, but later the Cassian fauna enjoyed a varied and rapid 

 development, and lived on good terms with the Reef-fauna of the Cipit Limestones. 



o. The fossiliferous marls and Cipit Limestones of Cassian age in Enneberg are 

 succeeded by a calcareous and dolomitic rock, which is of the same age as the upper 

 horizons of the calcareous and dolomitic marine deposits of mid-Triassic age in the 

 south and south-west. Taking one or two parallel lines of section north and south 

 through the inner Cassian belt of deposit, we find that Schlern dolomite succeeds, 

 in the west or Groden area, an extremely irregular submarine relief of volcanic, 

 sedimentary, and reef-rocks of "Wengen and Cassian age ; in the Enneberg area it 

 succeeds reef -rocks and the famous fossiliferous Cassian marls of Stuores meadow; 

 in the Ampezzo and easterly regions it succeeds reef-rocks and fossiliferous marls, 

 belonging to a somewhat later palaeontological zone, Upper Cassian. 



6. Contemporaneous faulting and volcanic action were the cause of mid-Triassic 

 heteropism in South Tyrol. 



Hence, so far as positive evidence goes, the Coral rocks of South 

 Tyrol in the Wengen and Cassian period are not the majestic 

 mountain massifs of dolomite, but much less obtrusive, lenticular 

 masses of limestone. And one general law may be said to govern 

 the Wengen and Cassian period in Groden, Enneberg, and Ampezzo, 

 a wandering north-eastwards of the Wengen and Cassian fauna 

 (including the special reef-fauna of the Cipit Limestones) consequent 

 on the cessation of volcanic activity along the immediate southern 

 boundaries of the Cassian-Enneberg sea, and the increasing sub- 

 sidence of these areas. During the subsiding movement, sea algse 

 and large Mollusca pressed northward. The shallow-water Cassian- 

 Enneberg fauna, no longer enjoying the same favourable conditions 

 as before, retreated into moi-e and more limited localities and 

 gradually gave place to its lineal descendants, the shallow-water 

 fauna of Raibl times. This transitional period paved the way for 

 the complete recovery of normal conditions in Fassa, Groden, and 

 Enneberg. As Mojsisovics has said. South Tyrol in Eaibl times 

 " participated once more in the general movements of Alpine areas." 



{To be concluded in our next Number.) 



