146 Miss M. M. Ogilvie—The U. Trias of St. Cassian. 



Both Eichthofen and Mojsisovics are of opinion that the Cassian 

 and Eaibl beds with their characteristic faunas are esst-ntially of 

 lilnited occurrence, having been deposited in occasional lagoons and 

 quiet bays. 



My personal mapping of the stratified deposits near St. Cassian 

 and at Seeland Thai and Cortina has enabled nie to show that a 

 further subdivision of the Wengen and Cassian strata is possible and 

 necessary ; and the detailed study of the rocks and fossils makes it 

 clear that each of these proposed subdivisions is distinguished by 

 both lithological and palaeontological characters peculiar to itself. 

 The most natural grouping of the strata seems to me to be as follows 

 in descending; order : — 



Dachstein Kalk 

 Eaibl Beds 



/'ScHLERN Dolomite 



O o > 

 Oh-ts O 



1 g ° 



- flO 



Cassian Beds. 



Upper Cassian 



.A greyish -white dolomite, rarely limestone; the 

 rock is stratified, and usually of compact character. 

 Megalodon triquetiis (Wult'.). 



.Dolomitic breccias, bituminous limestones, sand- 

 stones, beds of gypsum, pure dolomite, and 

 variegated ferruginous clays. 

 Fossils: Ostrea montes-caprilis (Klipstein), 3Iyo- 

 phoria Kefirsteinii (Goldf.), Cordis Mellinghi 

 (Hauer), etc. 



..A dolomite of drusy, highly crystalline character; 

 fossils rare ; corals, encrinites, bivalves. 





Fossiliferous marls, dark clays, light grey shales 

 and interstratified limestones. 

 Frelongei zone. ) Monllivaitia crenata (Miinst.), Cladophyllia sub- 

 dichotoma (Sube.), Aiioplophora Miinsteri 

 (Wissra.), Avicula Gta, d'Orb. 

 Marls, impure clays and shales with interstratified 

 oulitic sandstones and limestones, and beds of 

 arragonite, the whole series showing admixture 

 of volcanic mud. 

 Fossils few : Mytilus Miinsteri (Klipst.), Encrinites, 

 also plant-remains. 

 ) Dark fossiliferous marls and clays and interstratified 

 [ beds of hard fossiliferous limestone. 

 j Isastrcea GiJmbeli (Laube.), Nucula lineata (Goldf.), 

 Cassia iiella decussata (Miinster), Koninckia Leon- 

 /«(??•«?« (Wissm.), IWebrutitla indintiHcta (Beyrich), 



Middle Cassian 



or 

 Muren zone. 



Lower Cassian 



or 

 Stuores zone. 



c i; 



■ o 



p 



g S 5 



Wengen Beds. 



Up. Wengen. 



Lr. Wengen. 



— Breccias (composed of limestone and volcanic ma- 

 terial), thin-banded limestones and clays, thick 

 beds of brownish sandstone — arragonite beds. 

 Posidomiinya We/igensis (Wissmann), Trachyceras 

 fiircntinn (Miinster). 

 ( b. Tufaceous sandstones & impure limestones ; black 

 eruptive tuffs with or without augite porphyry. 

 Daonella Lommdi (Wissm. sp.), and plant-remains 

 I [Eqnisetites, etc.) 



I a. Halobia shales, -Daonella Lommeli (Wissm. sp.) 

 1^ (of local occurrence). 



Horizon of the ' Buchen- 

 steiner beds and B. 

 dolomite ' (Mojs.). 



Augite porphyry or volcanic series, and Buchenstein strata. 



