298 BOTANY AND PALEONTOLOGY 



prairies, and direct the future construction of railroads, which are gene- 

 rally attracted by the coal, as by a powerful magnet. 



It was, therefore, with a due consideration to the interests of the State 

 that the Governor of Arkansas, and the State Geologist of the Survey, 

 ordered that researches should be made to reconnoitre carefully the extent 

 of the coal-basin of Arkansas, and its capacity, or the number of coal- 

 strata which it contains in the whole thickness of the measures. 



The coal-measures of the United States, at least in the places where 

 they have received their full development, appear divided into four mem- 

 bers by three different and thick strata of sandstone. The upper member 

 rests upon a stratum named, in the Reports of the Kentucky Geological 

 Survey, the Anvil-Mock sandstone, and contains some coal-beds, which 

 are apparently extended over a wide area, but which until now have not 

 been found of workable thickness. The second member in descendinof 

 order is underlaid by the Mahoning sandstone, another great sandstone, 

 sometimes conglomeratic in its upper part. This member, four to five 

 hundred feet in thickness, contains, especially in Pennsylvania, the great 

 Pittsburg coal-bed, and in Kentucky as many as five workable beds of 

 coal, one of which, corresponding, by its position, with the Pittsburg coal, 

 is generally from four to five feet thick. The third member, of about the 

 same thickness as the former, lies between the Mahoning sandstone and 

 the Millstone Grit series, or Conglomerate Formation, and contains also 

 from four to six workable strata of coal, one of which is generally from four 

 to six feet thick. This Millstone Grit, a variable formation, considering 

 either the thickness or the nature of its strata, has been considered as the 

 base of the true coal-measures, and the coal-bearing strata underlying it 

 have been named by some geologists the False Coal-measures. But the exa- 

 mination of these strata, and the comparison of the fossil plants found in 

 connection with them, tend to prove that this fourth member which de- 

 scends from the base of the Millstone Grit to the Subcarboniferous Lime- 

 stone, cannot be separated from the whole of our coal-formations ; that it 

 is a true member of them ; that in some countries it contains two or three 

 workable beds of coal, which can be as profitably worked as any bed of 

 the other members. 



As has been reported in the first volume of the Geological State Survey 

 of Arkansas, all the coal-beds of the State appear to belong to the lowest 

 member of the coal-formations, underlying the Millstone Grit. At least, 

 all the hills or mountains at the base of which coal -strata have been found 

 in Arkansas, are formed of shales and of various kinds of sandstone, all 

 belonging to the Conglomerate Series, which reach here a great thickness. 

 Even at the top of the highest mountains, I have failed to discover a trace 

 of the coal or of the other measures which follow the Millstone Grit in 

 ascending order. This cannot lead to the conclusion that the prospect for 



