42 THE GEOLOGIST'S TRAVELING HAND-BOOK. 



Relics of vegetation are occasionally found in the Triassic, in the form of 

 highly compact and bituminous lignite, the longitudinal sections exhibiting the 

 fibrous structure of the wood, whence it was formed. This lignite, occurring 

 sometimes in seams of two or three inches in thickness, amid dark shales, has 

 been a fertile source of delusion, some persons having been induced by the hope 

 of finding valuable coal-mines, to waste much labor in the search. Although the 

 Richmond and North Carolina coals are Triassic, all the geological facts discoun- 

 tenance the notion that it contains coal in New Jersey and Pennsylvania, the 

 detached fragments of plants, which we meet with in the form of lignite, having 

 evidently been loosely drifted into these sediments from the land. Prof. Emmons 

 says there is nothing which can be regarded as equivalent to the coal measures of 

 the Chatham (N. C.) and Richmond (Va.) series in the northern beds. All this 

 formation was produced at a period subsequent to the great Carboniferous or coal- 

 bearing rocks. There are great numbers of fossil fish in the Trias of New Jersey 

 and Connecticut valleys, among them twenty species of ganoids; also the famous 

 bird-tracks of Dr. Hitchcock. See notes 7 and 8 on Massachusetts. Fossil plants 

 are numerous in the Trias of Virginia and North Carolina. 



When a large portion of the pebbles are of limestone, in the Triassic con- 

 glomerate, and the cementing red earth which unites them, contains an adequate 

 quantity of the same material, the rock possesses the character of a marble, as on 

 the Potomac River. The Portland stone, or reddish-brown sandstone, so much 

 used for building purposes in New York and other eastern cities, is from the 

 Triassic formation. 



Extensive mines for copper ore have been wrought in the Triassic, in the State 

 of New Jersey, the ore occurring in every case adjacent to igneous traps, but not 

 in contact with them. All these mining operations have failed, on account of the 

 ore being diffused or disseminated through the mass of the formation, and not 

 being found compacted in regular veins. In Europe, the upper part of the 

 Triassic is called Keuper, or copper. 



Trap-Dikes. Numerous parallel ridges and dikes of Trap, some of them 

 many miles in length, and with the elevation of mountains 400 feet high, and 

 ridges of all sizes, traverse the Triassic. Indeed, nearly all the trap-dikes are 

 confined to this formation. The material which composes these rough, rocky 

 ridges, undoubtedly protruded in a state of fusion, slowly and gently through long 

 narrow fissures, produced by the gaping asunder of the rocks* and not by 

 enormous violent disruptions, like those of volcanoes, as the strata through which 

 they passed are very little disturbed, and the dip of the strata is very little 

 affected by them. These trap-dikes have burst through the red shale and sand- 

 stone, after they were deposited, overflowing, while in a melted and highly heated 

 condition, the adjacent beds, and greatly altering their texture, color and mineral 

 aspect. The finest of these trap-dikes is the Palisades, on the west side of the 

 Hudson River, above Jersey City, and extending north of that place. (See note 5, 

 in chapter on New York). The tunnels and deep railroad-cuts through it, hi Jersey 

 City, afford good opportunities to observe the appearance of the stone, the principal 

 constituents of which are hornblende, feldspar, and titaniferous oxide of iron. 

 The little mountain of iron ore at Cornwall, in Lebanon county, Pennsylvania, was 

 thrown up by a trap-dike of the Triassic. 



