THE TRIASSIC PERIOD. 



20S 



extraordinary series of fossiliferous beds, replete with marine 

 fossils. Sir Charles Lyell gives the following table of these 

 remarkable deposits : — 



I. Koessen beds. 



(Synon>Tns, Upper St , 

 Cassian beds of Escher\ 

 and Merian.) 



2. Dachstein beds. 



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



'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. Aviada coniorta, Pecien Valo- 

 niensis, Cardiiim Rhceticum, Avicula 

 ijiceqnivalvis, Spirifer Alunsieri, 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 2CX)0 feet. 

 Upper part fossiliferous, with some 

 ( strata composed of corals [Lithoden- 

 dron.) Lower portion without fossils. 

 Among the characteristic shells are He- 

 f7iicardiu?n Wtilfeni, 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 A??imonites, besides 

 Ceratites and Goniatites, Beleinnites (rare), 

 Forcellia, Fleuroio??iaria, Trochus, Mono- 

 tis salinaria, &c, 



'A. Black and grey lime- 

 stone 1 50 feet thick, al- 

 ternating with the un- 

 ( derlying Werfen beds. 

 j B. Red and green shale 

 I and sandstone, with 

 \_ salt and gypsum. 



Hallstadt beds 

 (or St Cassian). 



A. Guttenstein beds. 



B. Werfen beds, base of 



Upper Trias ? 

 Lower Trias of some 

 geologists. 



Among the fossils 

 are Ceratites 

 cassiatius, My- 

 acites fassaen- 

 szs, Naticella 

 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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