476 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



coloured limestone which he had termed "Arlberg Limestone"; 

 in Bavaria and North Tyrol the Partnach shales are succeeded 

 by a light, pure limestone (afterwards called "Wetterstein 

 Limestone") with Chemnilzia and -Diplopora annulata. These 

 limestones were identified by Richthofen with the Hallstatt 

 limestone in the Salzkammergut. 



Richthofen's demonstration of the occurrence of the 

 Raibl strata in North Tyrol is especially important. Oolitic 

 limestones and plant-bearing sandstones associated with rauch- 

 wackes and gypsum had been observed by Escher in Vorarl- 

 berg, and called Lower St. Cassian strata. The same series 

 observed by Pichler and Giimbel in North Tyrol and Bavaria 

 were called " Cardita Strata," from the frequency of the fossil 

 Cardita crenata. Like Escher, Pichler and Giimbel also 

 referred them to the age of the typical St. Cassian strata in 

 South Tyrol. The occurrence of a fair number of fossils 

 identical with those in the south Alpine Raibl strata led 

 Richthofen to identify this group of fossiliferous strata in the 

 northern Alps as " Raibl Strata," although he admitted that the 

 Raibl strata in North Tyrol seemed to have a greater number 

 of fossils in common with the St. Cassian series than was the 

 case in the typical " Raibl Strata " at Raibl in Carinthia. He 

 supposed, therefore, that the Raibl strata in North Tyrol were 

 slightly older than those in the southern Alps. 



The unfossiliferous calcareo-dolomitic masses of rock above 

 the Raibl strata in Vorarlberg were compared by Richthofen 

 with the Dachstein limestone in the Salzkammergut; in Vorarl- 

 berg, the dolomitic masses passed upward into Kossen marls 

 and limestones with Megalodon triqueter. The tectonic rela- 

 tions in Vorarlberg were elucidated by Richthofen by means of 

 a number of excellent geological sections. 



Another work by Richthofen, which was destined to have an 

 even wider influence upon Alpine geology than his admirable 

 exposition of the Triassic succession in North Tyrol and 

 Vorarlberg, was his Geognostische Beschreibung der Umgegend 

 von Predazzo, St. Cassian, und der Seisser Alp. This classical 

 work appeared as an independent publication in the year 1860, 

 but the author's geological observations had been taken in the 

 summer of 1856. The work was greeted on its appearance 

 with the highest recognition from all sides, and the author, 

 who was little over twenty at the time, was looked upon as one 

 of the first Alpine geologists. 



