406 MESOZOIC TIME. 



As the several regions are isolated from one another, they naturally differ widely in 

 the succession "of beds and in the character of the rocks. They cannot, therefore, be 

 brought into parallelism by reference to mineral characters. 



In the Connecticut River region, in Massachusetts, according to Hitchcock, these beds 

 consist, beginning below, of — 



1. Thick-bedded sandstone through nearly half the thickness, in some parts a con- 

 glomerate. 2. Micaceous sandstone and shale, with fine-grained sandstone. This shale 

 sometimes contains very thin coal seams and fossil fishes. 3. A coarse gray conglom- 

 erate, the stones sometimes a foot or more through. 



The material has come from the crystalline rocks adjoining, — the granyte, gneiss, 

 mica schist, etc., and has not, in general, been much assorted by the action of currents 

 or waves. The thickness has not been satisfactorily ascertained, owing to the extent to 

 which the beds are covered by the stratified Drift and alluvium of the valley, conceal- 

 ing all faults: it cannot be less than 3,000 feet, and may be more than double this. 



At Southbury and near Middlefield, Ct., and near Springfield, Mass., there is an im- 

 pure gray or yellowish limestone, fitted for making hydraulic lime. 



In Virginia, the rocks consist, as in New England, of the debris of the older crystal- 

 line rocks with which they are associated. Near Richmond, where the beds are 800 

 feet thick, there are 20 to 40 feet of bituminous coal, in three or four seams, alternating 

 with shale ; and in some places the coal shales directly overlie granyte and gneiss. The 

 coal is of good quality, and resembles the bituminous coal of the Carboniferous era. It 

 contains, according to Hubbard (Am. J. Sci., xlii. 371, 1842), 30 to 35 per cent, of vola- 

 tile 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 1,500 to 2,000 feet in thick- 

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

 stones, in some places 1,200 feet thick. 3. The Upper red or mottled sandstones and 

 marly tes, 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 conl 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 resemblance 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 Triassic period. Although very widely 

 distributed over the eastern slope, south of the parallel of 38°, they seldom contain fos- 

 sils; and the few found — occasional pieces of fossil wood — are not sufficient to settle 

 the question. The beds are known to underlie unquestionable 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 Carboniferous. They therefore belong either to the 

 Triassic or to an inferior part of the Jurassic formation. 



(c.) Rocky Mountain region and Pacific Border. — In the Elk Mountains, of 

 the western part of the Colorado territory, several of whose peaks are over 14,000 feet 

 high, the upper part, for several thousand feet, consists of Triassic, or Triassic and Ju- 

 rassic, sandstones and marlytes, nearly horizontally stratified, overlying Carboniferous 

 strata (Hayden). The high Wahsatch and Uintah Mountains, east of the great Salt 

 Lake, are also largely Triassic and Jurassic over Carboniferous, and so are part of the 

 Humboldt ranges west of this lake : in the Wahsatch, the beds consist of sandstones and 

 dolomitic limestones, 1,800 feet thick (King). The Triassic of the Sierra Nevada has 

 been observed in California, according to Whitney, in El Dorado County, at Spanish 

 Flat, in Plumas County, near Gifford's Ranch, etc.; also in Owen's Valley, along the 

 western flanks of the Inyo and White Mountains. 



