452 TRIAS OF THE UNITED STATES. [Ch. XXH, 



But tne plants upon the whole are considered by Professor Heer to 

 have the nearest affinity to those of the European Keuper. When 

 Sir Charles Bunbury compared them in 1847 to the fossil plants of 

 Neueweld near Basle, and of other plant-bearing rocks near Baireuth, 

 he supposed, as linger had done before him, that those localities were 

 Liassic, whereas geologists afterwards determined them to be of Upper 

 Triassic date. 



The fossil fish are Ganoids, some of them of the genus Catopterus, 

 others belonging to the Liassic genus Tetragonolepis [^Echmodus), see 

 fig. 452 p. 421. Fossil mollusca are very rare, as usually in all coal- 

 bearing deposits, but two species of Entomostraca called Estheria are 

 in such profusion in some shaly beds as to divide them like the plates 

 of mica in micaceous shales (see fig. 490). 



Fig, 490. 



a. Estheria ovata. b. Young of same. 



Oolitic coal-shale, Eichniond, Virginia. 



These Virginian coal-measures are composed of grits, sandstones, 

 and shales, exactly resembling those of older or primary date in America 

 and Europe, and they rival or even surpass the latter in the richness 

 and thickness of the coal-seams. One of these, the main seam, is in 

 some places from 30 to 40 feet thick, composed of pure bituminous 

 coal. On descending a shaft 800 feet deep, in the Blackheath mines 

 in Chesterfield County, I found myself in a chamber more than 40 feet 

 high, caused by the removal of this coal. Timber props of great 

 strength supported the roof, but they were seen to bend under the 

 incumbent weight. The coal is like the finest kinds shipped at New- 

 castle, and when analysed yields the same proportions of carbon and 

 hydrogen — a fact worthy of notice when we consider that this fuel has 

 been derived from an assemblage of plants very distinct specifically, 

 and in part generically from those which have contributed to the for- 

 mation of the ancient or palaeozoic coal. 



New Red Sandstone of the Valley of the Connecticut River. — In a 

 depression of the granitic or hypogene rocks in the States of Massa- 

 chusetts and Connecticut, strata of red sandstone, shale, and con- 

 glomerate are found, occupying an area more than 150 miles in length 

 from north to south, and about 5 to 10 miles in breadth, the beds 

 dipping to the eastward at angles varying from 5 to 50 degrees. The 



