On the Chemical and Mineralogical Evidence as to the Origin of the Dolomites of Southern Tyrol

Abstract

I. I ntroduction . T he country of the ‘Dolomites’ has long been classic ground to geologists. The researches of Dolomieu at the end of the eighteenth century, and of L. von Buch early in the nineteenth, first aroused the interest of geologists in the district. Their attention at first was mainly directed to speculations concerning the mode of origin of the mineral, named after the French geologist, of which the mountains are so largely composed; this question, even at the present day, is far from settled. The stratigraphy of the district has always presented many points of difficulty. The earlier observers, struck by the contrast in scenery and composition between the bold, precipitous, dolomite-masses and the marls and stratified tufts of the green pasture-lands or ‘Alpen,’ were at a loss to explain their mutual relations, especially as very few fossils were at first discovered in any of the deposits. In 1834, however, Graf Münster, who had examined the strata near St. Cassian, enumerated, and (inpart) described and figured 400 species of fossils from them, and subsequent observers have added largely to the number. The precise age of these deposits, which had till then been a matter of discussion, was settled by the examination of their fossil contents. It was shown not only that the beds were of Triassic age, but that, unlike the Trias of most of the European areas, they had been deposited under marine conditions. In 1845 Bronn suggested that the St. Cassian fauna had inhabited a shallow sea where