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instance of arrested growtli of this rock, so that one which did not 

 receive the covering was allowed to grow still further (if it did 

 grow) and reach the height which they saw, and the progress of 

 the others was stopped by the deposit which now caps them. In 

 other words this cap in some way or other arrested the growth of 

 the Dolomite in the case of the lower mountains, whereas the 

 Langkofel was not arrested, and the growth continued 2,500 or 

 more feet higher. 



There was another theory by a Canadian, Mr. T. 8. Hunt, 

 who said the Dolomites are accounted for by the action of the sea 

 water, and that it was a metamorphic change, the sea water being 

 at boiling point for a long time. He thought that might be 

 admitted in the case of the Dachstein or upper Dolomite, but not 

 for tlie bed they were now considering, called the " Schlern 

 Dolomite." 



The fourth theory was that of Richthofen, and it seemed to 

 be generally accepted. He said that " The Schlern plateau was 

 a coral reef, and that the entire formation, called ' Schlern 

 Dolomite,' had in like manner originated through animal activity." 



His idea was that it was built up by coral polyps — of which 

 there were hundreds of different species — and that the entire 

 formation had oi'iginatcd through their constructive activity. That 

 was rather a large theory to accept, an 1 yet, on the whole, he was 

 inclined to accept it. The reasons Richthofen gave were these : 

 The form of the masses, falling down sharply on each side. Their 

 construction was very similar to au engraving of a coral island 

 (Bolabola) which was in Pi'ofessor Darwin's book on '' Coral reefs 

 and coral islands." Then Richthofen pointed to the isolation of 

 the Dolomites from similar masses in their neighbourhood, and said 

 there was evidence from other sources that the district they were 

 now considering was undergoing a slow depiession at the time of 

 Dolomite formation. He pointed out that the Raibl bed, whicli 

 lay in many instances over the " Schlern Dolomites," contained 

 the fauna of a shallow sea, as much as to say that the coral polyps, 

 which could only work at the surface or within 1 50 feet of the 

 surface, received that deposit on them while the sea was still 

 shallow, because of the numerous fossils found in tint little Raibl 

 bed. Then he pointed out that there was evidence of previous 

 volcanic activity in this region, and the coral polyps found volcanic 

 ashes very favourable ground for building upon, ;ind also that 

 there were some coral reefs in the South Pacific equal in depth to 

 the Dolomite mountains themselves. The Lecturer understood 

 that it had been proved that South Tyrol was during the latter 

 portion of the Trias Period in a condition of gradual depression 

 after a period of sub-aqueous volcanic activity, and that a great 

 upheaval had since taken place, lifting the ocean bed up to the 



