94 ON THE GEOLOGY AND NATURAL HISTORY 
Feet. 
distributed somewhat sparingly throughout the bed of sandstone. It also contains some fine impressions 
of dicotyledonous leaves. 
2. Dark indurated carbonaceous clay, . : : i 2 : 5 : : 4 : : _ a3 
3. Lignite, of an average degree of purity, : 2 
. Indurated clay with a reddish tinge containing much carbonaceous matter, D) 
oO 
. Light yellow clay with seams of carbonaceous matter disseminated through it, a sort of fine clay, 4 feet 
exposed above the water-level. 
Thirteen miles above Fort Clark, at Red spring, on the right side of the Missouri, are a 
long series of nearly perpendicular bluffs, exposed by the river. This is the best locality 
for the collection of fossil plants I have yet seen. They are finely preserved, occur in 
ereat profusion, and belong nearly all to dicotyledonous trees. The following is a vertical 
section of the different beds in descending order, as they appear in this range of hills: 
Feet. 
1. Ferruginous marl, . : : : 6 : : ; ¢ é , : é . : 5 lO 
2. Variegated bands of argillaceous grits, —. : : 5 ‘ : : j : 6 : . 80 
3. Seam of impure reddish lignite, 2 inches. 
4. Yellowish gray grit, with numerous concretions, in horizontal layers, filled with beautiful impressions of 
leaves, . : ‘ : é : ; 3 : ; ; F ; : ‘ j . 10 
5. Seam of lignite, 2 inches. 
6. Yellowish gray sand with argillo-calcareous concretions, laden with impressions of dicotyledonous leaves, 10 
7. Harthy lignite, 8 inches. 
8. Yellow and drab clay and sandstone, containing argillaceous concretions with vegetable impressions, . 15 
9. Dark reddish earthy lignite, 4 inches. 
10. Yellow argillaceous grit, . 6 0 . . : 6 : ‘ : : 6 : : 5 Al) 
i1. Alternate layers of lignite and clay varying in thickness at different localities within a distance of four 
miles, : : : . : : : : : 6 6 9 : é : . 4to 15 
12. Heavy-bedded friable sandstone, very ferruginous, varying in color from yellow to gray and yellowish gray. 
Same bed, I think, as seen at Fort Clark and on the summit of Square hills, containing so many fossils. 
Here we have Melania Nebrascensis, Paludina multilineata, and Corbula matriformis, . 6 . 40 
13. Seam of lignite, 2 inches. 
14. Gray argillaceous grit, . é 0 0 é . : . : ; 6 6 . : . 4 
15. Lignite of excellent quality, . : 0 0 é . ‘ : 2 . . . : o 
16. Bluish gray clay, slightly arenaceous, : . : 0 0 . . 0 : : De eneiae aa, 
17. Lignite near water’s edge, quite pure, . 0 0 6 0 0 0 : : : . 3 to 4 
Beneath bed 17 may be seen at low water a heavy-bedded gray sandstone. 
In speaking of lignite as of a good quality, I mean, that it contains a small amount of 
earthy material, but I have not yet seen any of it that would be of much value for economi- 
cal purposes.* Specimens from this locality and from Fort Berthold, forty miles above, 
* T am satisfied that some of the beds of lignite, especially those on the Yellowstone, can be used for fuel, when 
the country is sufficiently settled to induce a demand for it. There are some excellent beds of lignite on the North 
