692 



THE WONDERS OF GEOLOGY. Lect. VII. 



suffered the least displacement. In the coal-fields where 

 the boldest flexures of the Appalachian chain occur, and 

 the strata have actually been overturned, as near Pottsville, 

 the coal is invariably changed into anthracite.* 



The carboniferous system of the United States presents 

 all the essential characters of that of England : the same 

 remarkable phenomenon of the prevalence of Stigmarice in 

 the underclay of the coal-beds, occurs as constantly as in 

 the European coal-fields. Thus in the coal-mines of 

 Blossberg, Pennsylvania, the underclays contain Stigmariae 

 with their rootlets extending in all directions, as in the 

 underclays of the Welsh coal-measures 3,000 miles distant. 

 At Pottsville, where the coal strata are vertical and worked 

 in the open air, the same phenomenon appears. " Several 

 of the coal seams, ten feet thick, having been removed, a 

 void space was left, and in the wall on one side, correspond- 

 ing to the roof, were shales full of ferns, lepidodendra, cala- 

 mites, &c. ; while the other side of the trench was formed of 

 the underclay, abounding in stigmariae. These phenomena 

 lead to conclusions respecting the origin of coal from 

 plants not drifted, but growing on the spot."f But through- 

 out some of the beds of underclay, leaves of fern are plenti- 

 fully dispersed, though the stigmariae are apparently 

 imbedded in their natural position. J As in Europe, the 

 marine shells and corals so abundant in the limestone, 

 seldom appear in the coal ; but Mr. Lyell observed a bed 

 of black bituminous shale, ten or twelve feet thick, full of 

 marine shells, interstratified with the coal, at Frostburg.§ 



21. Organic remains of the Carboniferous Sys- 

 tem. — The fossils entombed in these deposits comprise 



* See the section of the country between the Atlantic and the Missis- 

 sippi, through the Alleghanies; Mr. Lyell's Travels in America, 

 p. 92 ; and the admirable geological map of the United States, in the 

 same work. 



f Ibid. pp. 62, 85. J Ibid. p. 18. § Ibid. p. \9. 



