THE TRIASSIC PERIOD. 



205 



extraordinary series of fossiliferous beds, replete with marine 

 fossils. Sir Charles Lyell gives the following table of these 

 remarkable deposits : 



Strata belcnv the Lias in the Austrian Alps, in descending order. 



i. Koessen beds. 



(Synonyms, Upper St 

 Cassian beds of Escher\ 

 and Merian.) , 



2. Dachstein beds. 



3. Hallstadt beds 



(or St Cassian). 



4. A. Guttenstein beds. 

 B. Werfen beds, base of 



Upper Trias ? 

 Lower Trias of some 

 geologists. 



Grey and black limestone, with calcareous 

 marls having a thickness of about 50 

 feet. Among the fossils, Brachiopoda 

 very numerous ; some few species com- 

 mon to the genuine Lias ; many pecu- 

 liar. AvicTila contorta, Pecten Valo- 

 niensis, Cardium Rhceticum, Avicula 

 inczqnivalvis, Spirifer Miinsteri, Dav. 

 Strata containing the above fossils al- 

 ternate with the Dachstein beds, lying 

 next below. 



White or greyish limestone, often in beds 

 three or four feet thick. Total thick- 

 ness of the formation above 2000 feet. 

 Upper part fossiliferous, with some 

 strata composed of corals (Lithoden- 

 dron.) Lower portion without fossils. 

 Among the characteristic shells are He- 

 micardium Wulfeni, Megalodon triqueter, 

 and other large bivalves. 



Red, pink, or white marbles, from 800 to 

 1000 feet in thickness, containing more 

 than 800 species of marine fossils, for 

 the most part, mollusca. Many species 

 of Orthoceras. True Ammonites, besides 

 Ceratites and Goniatites, Belemnites (rare), 

 Porcellia, Pleurotomaria, Trochns, Mono- 

 tis salinaria, &c. 



A. Black and grey lime- 

 stone 150 feet thick, al- 

 ternating with the un- 

 derlying Werfen beds. 



B. Red and green shale 

 and sandstone, with 

 salt and gypsum. 



Among the fossils 

 are Ceratites 

 cassianns, My- 

 acites fassaen- 

 sis, Nat ice La 

 costata, &c. 



In the United States, rocks of Triassic age occur in several 

 areas between the Appalachians and the Atlantic seaboard ; 

 but they show no such triple division as in Germany, and their 

 exact place in the system is uncertain. The rocks of these 

 areas consist of red sandstones, sometimes shaly or conglomer- 

 atic, occasionally with beds of impure limestone. Other more 

 extensive areas where Triassic rocks appear at the surface, are 

 found west of the Mississippi, on the slopes of the Rocky Moun- 

 tains, where the beds consist of sandstones and gypsiferous 

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