OF ARKANSAS. 317 



would be forced to consider each peculiar bed of coal as a separate forma- 

 tion or rather as an epoch. 



The other conclusions taken from the examination of the table are in 

 favor of the horizontal identity of all the coal strata of Arkansas, the ap- 

 parent difference in their species resulting from the small number of fossil 

 plants which have been found at some localities. Thus the coal of James' 

 Fork of Poteau where, after Male's coal-bank, the largest number of fossil 

 plants were seen, has, in twenty-five species, ten species in common with 

 Male's coal, some of which are new and apparently truly characteristic of the 

 subconglomeratic coal. Of ten species collected at Jenny Lind coal-bank, 

 eight were seen also at the James' Fork of Poteau. Seven of the eight 

 species of Lee creek coal have been found also at Male's, and of eleven 

 fossil plants found in the shales at Frog Bayou, seven belong also to Male's 

 coal-bank. Taking into consideration the insufficiency of the researches 

 and the distance of the coal-banks where the plants were found, it is easily 

 admitted that this approximate identity of species shows with great proba- 

 bility, if not with certainty, that the coal-banks or strata reported above 

 are to be placed on the same geological horizon. 



AND FOSSIL PLANTS OF THE SAME FORMATION. 



The Lignite formation is easily distinguished from the Coal-measures, as 

 well by its distribution, its geological position, the chemical compounds of 

 its combustible matter, as by the plants by which it is accompanied. From 

 the few data which have been collected in Arkansas it appears that the 

 lignites of that State are found generally near the base of the Tertiary 

 measures.* They have been formed by an accidental deposition of a 

 certain quantity of wood, apparently transported by rivers or some other 

 agency, or even perhaps are composed of the heaped remains of trees 

 which grew in marshes and swamps at the place where beds of lignites are 

 now found. The areas which they cover with strata of combustible matter 

 is extremely variable. Sometimes they extend themselves for hundreds of 

 miles, preserving a constant horizon ; sometimes they have only a few feet 

 in diameter, and appear either thin or like a broken and heaped compound 

 of combustible black matter, irregularly placed at various horizons in the 

 same vicinity. Beds of Lignites are generally intermixed with clay or 

 sand. Their overlying strata are not shales, but mostly soft, black or yellow 

 plastic clay or sand. The numerous remains of plants found in this soft 

 matter are of course decayed, broken, and undistinguishable. 



The only bed of Lignites which I had an opportunity of examining in 



* See Sections in the Report of the State Geologist. 



