Miss M. M. Ogilvie— Coral in the " Bolomites" 59 



already considerably faulted have been affected in this way, the 

 ultimate results may seem conflicting. More especially might 

 this be expected in the Fassa or Rodella districts, but no such 

 complication would gainsay the striking analogy which the 

 "Eruptive Fault" of Fassa presents in its main tektonic aspects 

 with the faults of Buchenstein and the Groden Joch. 



VI.— Conclusions with regard to Coral Formations in the Dolomites. 



We are now in a position to examine more closely the points 

 of agreement and difference which Coral formations in the 

 Dolomites present with the various theories of Coral-reef growth. 

 Mojsisovics ^ has clearly shown to what a great extent variation in 

 the rate of subsidence and the depth of the sea-floor has influenced 

 mid-Triassic deposit in South Tyrol. Eothpletz, in his most recent 

 work,^ has discussed the entire question and brought forward the 

 importance of submarine banks of sediment. While I have attempted 

 to indicate an irregular sea-floor in Diagrams I. to IV., I designed 

 those diagrams mainly to show one or two other facts of almost 

 equal importance : (a) that coralline " Cipit Limestone " and Coral 

 Dolomite form comparatively small thicknesses of interbedded rock 

 and not the main body of the mountain masses; (fo) that Corals 

 began to grow in Wengen time on a submarine volcanic ridge on 

 the northern edge of a great area of subsidence, and travelled inward 

 and northward in Cassian time ; (c) that extensive banks of Coral 

 were formed in scattered localities during the Eaibl period of 

 shallower water and Dolomite deposit. 



The Coral-blocks and lenticular "Cipit Limestones" were, there- 

 fore, to begin with, members of a submarine barrier-ridge, and never 

 were strand-reefs. There was, from early Wengen time, an inner 

 protected part of the sea whose bed, so far from being deepened in 

 the way indicated either by Murray or Guppy, was constantly being 

 shallowed by the rapid accumulation of shore sediment and the 

 intermittent eruption of porphyry and lava. The movement was 

 one of subsidence, proved by the fact that the Corals moved north- 

 wards, or inwards, in the later Cassian periods, and gave place, 

 along the old Fassa-Groden barrier, to the formation of marine 

 Calcareous deposit. Probably occasional stationary intervals re- 

 tarded the subsidence of this inner sea, and were, so far, favourable 

 for Coral-growth. Several authors have called attention to the 

 evidence of the action of currents in those areas. The vicinity of 

 land is proved by the frequency of plant remains everywhere in the 

 Wengen sediments. In the Cassian strata of Enneberg these are 

 very rare ; on the other hand, in the Ampezzo district, fragments of 

 stems and leaves are common at certain horizons of Cassian and 

 also of Eaibl strata, and were not unlikely swept here by some 

 wide river-channel from the north-west. The area of depression, 



1 Mojsisovics, "Dolomit-Rifi'e," etc., pp. 505-510, and more especially for general 

 tektonic relations, chap. xvii. 



2 Eothpletz, " Ein geologischer Querschnitt durch die Ostalpen," Stuttgart, 1894, 

 pp. 52-67, "1st der Schlerndolomit ein KorallenrifE-Bildung "— a full discussion 

 of the question. 



