Miss M. M. Ogilvie — Coral in the " Dolomites. ^^ 7 



of plants are of frequent occurrence. Mojsisovics has proved that 

 these invasions came from a submarine volcano, probably in 

 Upper Fassa, w^hich " lay on the edge of the district of greater 

 subsidence " to the south. " In Triassic time, as we are taught by 

 the history of the Triassic reef masses, a certain protraction took 

 l^lace in the subsidence going on at the edge of the insular core of 

 older rocks to the north as compared with a more rapid subsidence 

 of the outer regions " (Mojsisovics, " Die Dolomit-Riffe von Siid- 

 Tirol und Venetien," p. 525). We may naturally suppose that 

 Augite Porphyry lavas foi'med irregular ridges on the disturbed 

 sea-floor, more especially near the eruptive centre. From the 

 beginning of this period we trace a marked diiference in the 

 deposits and fossil remains of the non-volcanic and volcanic areas 

 respectively south and north of the Upper Fassa ridge, and even 

 considerable variation within the shallow volcanic sea itself. A 

 representation of the sea-floor in this period is given in Diagram I. 



Corals found abundant " coigns of vantage " and were aided by 

 Echinodermata to form communities of organic life, often prevented 

 from farther growth by new volcanic invasions, but ever and auon 

 settling down afresh. The remains of these form the "Cipit blocks " 

 and " Cipit limestones," which were first observed by von Eichthofen 

 amid Cassian marls on the slopes below Schlern. Mojsisovics recog- 

 nized similar limestones appearing intermittently over the whole 

 area eastward. I have given special attention to the relations of 

 these limestones with the contemporaneous rocks, and shall at once 

 describe the more interesting results. 



They, and not the mountains of Schlern dolomite, deserve the 

 name of " Coral Eeefs " in South Tyrol. They never attain any 

 great thickness ; generally in highly volcanic periods they formed 

 mere isolated blocks composed of colonies of Corals and Echinoderms, 

 and closely wedged amongst tuify marls. In less volcanic periods 

 continuous beds spread over a larger area — sometimes suddenly 

 swelling out in lenticular fashion, sometimes perceptibly thinning 

 into deposits full of other classes of animals. Stratigraphically 

 considered, they occur as the equivalents of Cassian and Wengen 

 strata, and in a less degree of Schlern dolomite and Eaibl strata, and 

 they follow certain fairly definite laws of distribution. Diagrams 

 I. II. and III. represent successive stages in the history of the 

 heteropic deposition in South Tyrol during this part of the Triassic 

 era ; Diagram IV. represents approximately the occurrence of Cipit 

 Limestones in the contemporaneous series of rocks. In the Upper 

 Fassa and Schlern districts the Cipit or reef-limestones occur at various 

 horizons in the midst of volcanic earthy Wengen beds, or associated 

 with sedimentary beds containing Halohia Lommeli, Posidonomya 

 Wengensis, etc. They continue upwards in that district to the 

 base of the Schlern dolomite, but are associated, north of the 

 Schlern Mountain, in their higher horizons with characteristic 

 Cassian fossils. 



In Groden Joch and in Enneberg, the Cipit Limestones do not 

 make their appearance until the Wengen beds are giving place to 



