300 BOTANY AND PALEONTOLOGY 



stone"), which do not apparently contain any other fossil plants but some 

 leaves of Lepidodendron, resembling long blades of grass. 



Though the examination of these coal-beds was unsatisfactory, since 

 they were not opened and exposed to view, I have no doubt that the upper 

 one overlaid by "soapstone" is the first coal below the Millstone Grit, gene- 

 rally the only one developed at this geological station. It is ordinarily 

 overlaid by soft yellow shales, containing pebbles of carbonate of iron or 

 clay iron ore, and marked by remains of fossil plants, of which the most 

 common species, and often the only one present, is Lepidophyllum ; that 

 is, those leaves of Lepidodendron mentioned above. 



The shales of this coal are remarkably variable, either in their color, or 

 hardness of texture, according to the amount of bitumen or of iron depo- 

 sited while in the process of formation. On banks where they are exposed 

 at some length, one can see them insensibly passing from a yellow soft 

 soapstone mixed with clay iron ore to hard black shales, generally more 

 or less abundantly intermingled with pebbles of carbonate of iron, which 

 have mostly the form and the size of hen's-eggs. Sometimes these shales 

 are so thoroughly penetrated by oxide of iron, that they constitute a hard 

 and valuable iron ore. It is necessary to observe these changes in the 

 appearance of the shales of the subconglomeratic coal-beds in order to 

 account for the difference which may be found at various localities. 



The beds of coal at Fayetteville, though thin at the place where they 

 crop out, may be found in close proximity to it, have a thickness of 

 two feet, or perhaps more. But it would be useless, I think, to search 

 anywhere in Arkansas for a bed of coal below the Archimedes Limestone, 

 which is exposed at the base of the hills near the town. And as the Mill- 

 stone Grit formation does not, apparently at least, contain any limestone, 

 the presence of a stratum of this nature may at once be accepted as an 

 indication that coal in Arkansas cannot be found at a lower level. 



MALES COAL-BANK. HIGHER WATERS OF MIDDLE FORK OF WHITE RIVER. 



Ascending from Fayetteville to the top of the hills, on the higher waters 

 of the middle fork of White river, near Mr. Hubbert's farm, a very inte- 

 resting section is exposed from the base of the Subcarboniferous measures 

 to the upper part of the Millstone Grit series.* There, about one hundred 

 feet below the strata which mark the base of the Millstone Grit, and from 

 which it is separated by two beds of Subcarboniferous Limestone with 

 intervening blue shales, shaly sandstone and chert, there is a thick stratum 

 of coarse sandstone containing plants of the true coal epoch, viz., species 



* See Mr. E. T. Cox's Report, hereafter. 



