TRIASSIC PERIOD. 417 



Hubbard (Amer. Jour. Sci. 1842, xlii. 371), 30 to 35 per cent, of volatile 

 ingredients. 



In North Carolina, the beds rest on the crystalline rocks, and have been derived 

 from their wear. Emmons divides them into three groups, beginning below : — 



1. The Lower red sandstone and its underlying conglomerate, estimated at 

 1500 to 2000 feet in thickness. 



2. The Coal measures, including shales and drab-colored ripple-marked sand- 

 stones, in some places 1200 feet thick. 



3. The Upper red or mottled sandstones and marls, separated at times from 

 the bed below by a conglomerate. 



There are five seams of coal at the Deep River Mines, — the first (or upper), 

 and best, 6J feet thick. The coal resembles that of Richmond, and is valuable 

 for fuel. Emmons obtained 28 to 31 per cent, of volatile ingredients. The 

 beds below the coal are of much less thickness in the Dan River coal region 

 than in that of Deep River. Good argillaceous iron-ore abounds in the coal 

 region of North Carolina, so that in almost every respect there is a close re- 

 semblance to the coal regions of older date. Both at Richmond and in North 

 Carolina there are numerous coal plants in the beds, and many stems or 

 trunks stand as they grew, penetrating the successive layers. 



(b.) Western Interior region. — There is still some doubt as to the age of the 

 beds of the Rocky Mountains referred to the Triassie period. Although very 

 widely distributed, they seldom contain fossils ; and the few found — an occa- 

 sional piece of fossil wood and remains of Saurians — are not sufficient to settle 

 the question. The beds of the eastern slope are known to underlie unques- 

 tionable Jurassic beds at the Black Hills in Dakota and the Red Buttes 

 on the North Platte, and hence to occupy a position between the Jurassic 

 and Permian ; and to the latter they are unconformable. They therefore 

 either belong to the Triaseic or to an inferior part of the Jurassic formation. 

 The rocks of the Upper Colorado, according to Newberry, lie between the 

 Carboniferous and the Cretaceous, and the whole thickness is 2000 to 2500 

 feet. But it is not yet known whether all these beds are of the Triassic/or 

 whether they cover both the Triassie and Jurassic periods. A bed of lig- 

 nite with some coal plants was found by Dr. Newberry near the junction 

 of the Cretaceous and the inferior red sandstone, containing a few fossil plants, 

 which he observes may possibly be Jurassic, although it is not certain that 

 they may not be Cretaceous. 



II. Life. 



There are two remarkable characteristics of the American Trias- 

 sie period, according to the present state of discovery : — 



1. The paucity of all distinctively marine life in the beds of the 

 Atlantic border. 



2. The absence of life of every kind, excepting some fossil wood 

 and Eeptiles, from the beds of the Western Interior. 



There may have been on the Atlantic extensive coast-accumula- 

 tions formed, containing numerous marine fossils, as in Europe ; 

 but none such are now exposed to view. 



28 



