1863.] 299 [Lesquereux. 



be discussed with their publication : 1st. The relation of the 

 actual flora with that of the Tertiary. 2d. The comparative 

 identity of typical forms both on the Pacific and Atlantic shores. 

 By comparative identity I understand relation of the now living 

 plants on both the Atlantic and the Pacific shore, with the fossil flora 

 of the same country; the relation of the Vancouver Tertiary with the 

 California flora, and the relation of the Tertiary of Mississippi, &c., 

 with the Atlantic flora. Of course this does not indicate a relation 

 of vegetation between both sides of the continent, either at the Ter- 

 tiary epoch or now; on the contrary. 3d. The difi"erence of flora of 

 Europe and of America, at the epoch of the Tertiary, showing the 

 separation of both continents. You know that Heer argues, on a 

 supposed but unreal identity of typical forms at the Tertiary time, 

 and concludes in favor of a Continental connection, either by an 

 Atlantide, or something of this kind. 4th. The relation of forms of 

 the Tertiary and Cretaceous floras, &c., &c. . . . 



With this letter I send you two sections of the Arkansas conglo- 

 merate measures, and the underlying subcarboniferous measures. I 

 am, indeed, very sorry that my sections were not made with more 

 details and exact measurements ; but I am not answerable for the 

 deficiency. My assistant, Mr. Cos, had charge of the geological part 

 of our explorations, and ... we had for our measurements only an 

 aneroid barometer, which, though pretty good, gave us only approxi- 

 mate altitudes. 



The first general section, showing the true position of the coal in 

 relation to the inferior strata, was taken fourteen miles southwest of 

 Fayetteville, in Washington County, on the high waters of Middle 

 Fork of White Kiver. 



FEET. INCHES. 



1. Millstone grit in alternating beds of coarse, gritty sandstone, 

 conglomerate hard sandstone with small pebbles, ferrugi- 

 nous hard bands, and soft shaly sandstone and shale, . 300 



2. Gray laminated shales passing at some places to ferrugi- 

 nous, very hard conglomerate. Shale band, ... 2 



3. Coal, 16 



4. Hard, black fire-clay full of stigmaria, passing at the base 



to clay-iron ore, ......... 6 



5. Hard limestone with Encrinites, Terebratulae, Archimedes, 

 &c., &c. Upper Archimede limestone. It appears to be 

 united with the lower bed sometimes, and then thickens to 



20 feet, 10 



6. Blue soft shales with pebbles of carbonate of iron, . . 20 



7. Shaly sandstone (gray metal of the miners), ... 30 



