320 



PALEOZOIC TIME. 



the upturning and flexures the formation has experienced ; and the coal is an exceed- 

 ingly hard anthracite, because of the metamorphism. Still, the slates often contain 

 fossil plants, part of which are identical in species with those of Pennsylvania. Near 

 Portsmouth, at Aquidneck, three beds are reported to exist, 2 to 20 feet thick, and at 

 Case's, one of the three is 13 feet thick; at Providence, one, of 10 feet; at Valley 

 Falls, five, 6 to 9 feet; at Cumberland, two, 15 to 23 -feet; near Mansfield, several, 

 with the maximum thickness 10 feet. The earliest opening was made at Case's, near 

 Portsmouth, in 1808. 



(b.) Appalachian Region. — The Millstone-grit, at the base of the Coal-measures, in 

 Pennsylvania, is mostly a whitish siliceous conglomerate, with some sandstone layers 

 and a few thin beds of carbonaceous shale. It overlies the Subcarboniferous shale or 

 sandstone. At Tamaqua, the thickness is 1,400 feet; at Pottsville, 1,000 feet; in the 

 Wilkesbarre region, 200 to 300 feet; at Towanda, Blossburg, etc., where it caps the 

 mountains, it is 50 to 100 feet thick (H. D. Rogers). 



In Virginia, the thickness is in places nearly 1,000 feet; the rock is mainly a sand- 

 stone, but contains heavy beds of conglomerate. The conglomerate of the Subcarbon- 

 iferous, in a similar manner, becomes an arenaceous rock in Virginia. In Alabama, 

 the rock is a quartzose grit of great thickness: it is used for millstones. In Tennessee, 

 there are two heavy beds of conglomerate, with several heavy coal beds between them 

 and below both, which are generally referred to the "False Coal-measures," of the 

 Millstone-grit epoch, though the relations of the series with that of Pennsylvania have 

 not yet been determined by actual connected explorations. 



The great Anthracite region of Pennsylvania is largely Lower Carboniferous. The 

 Upper Carboniferous is present there (at Pottsville, Shamokin, and Wilkesbarre) up to 

 the top of the Pittsburg group (Lesley); but the rest does not extend so far eastward. 

 The greatest development of the Lower coal is in Pennsylvania; and of the Upper, in 

 the States farther west. The highest beds in the series appear to occur west of the 

 Mississippi, in Kansas, where they merge into the Permian. A section of the Coal- 

 measures in western Pennsylvania, to the top of the Pittsburg bed, is given on pages 

 311, 312. The following is a section of the part above this coal-bed, in Waynesburg, 

 Greene County, as published by J. P. Lesley, in his work entitled " Manual of Coal and 

 its Topography " : — 



Feet. 



1. Shale, brown, ferruginous, and sandy 30 



2. Sandstone, gray and slaty 25 



3. Shale, } T ellow and brown . 20 



4. Limestone, — the Great Limestone south of Pittsburg (including two Coal 



beds, 2| feet and 1 foot) 70 



' 5. Shale and sandstone 17 



6. Limestone 1 



7. Shale and sandstone 40 



8. Coal : 6 



9. Shale, brown and yellow 10 



10. Sandstone, coarse, brown 35 



11. Shale 7 



12. Coal •' li 



13. Limestone 4 feet, shale 4, limestone 4, shale 3 15 



14. Shale 10 feet, sandstone 20, shale 10 40 



15. Coal • 1 



16. Sandstone (at Waynesburg), with 4 feet of shale 24 



The thickness in Pennsylvania, according to Rogers, is from 2,500 to 3,000 feet. The 

 anthracite region, as shown on the map, page 310, is divided into three ranges, a south- 

 ern, a middle, and a northern. Near Pottsville, the southern or Schuylkill range in- 

 cludes fifteen coal-beds, which vary from three to twenty-five feet in thickness; and the 

 whole thickness of the coal is one hundred and thirteen feet, eighty feet of it market- 



