122 PROCEEDINGS OF THE ACADEMY OP 



Section of Tertiary beds thirteen miles above Fort Clark. 



30 feet. 



Ferruginous sandy marl passing downwards into variegated 

 argillaceous grits. 



B 2 inches. ( Heara of impure reddish lignite. 



C 10 to 12 

 feet. 



Yellowish-gray friable grit, with numerous argillaceous con 

 cretions in horizontal layers, containing beautiful impressions of 

 leaves, like those of PIqtanus, Acer, Ulmus, &c. 



;D i 3 inches | Seam of lignite, very much mixed with clay and sand. 



E 



10 feet. 



Yellowish-gray grit, very friable, and containing argillaceous 

 concretions charged with leaves of same species of plants as above 



F I 3 inches, j tSeam of earthy lignite 



15 feet. 



Yellow and drab clay and friable sandstone, containing argil- 

 laceous concretions with remains of plants like those above. 



H I 4 inches. | Dark reddish earthy lignite. 



20 feet. 



Yellow arenaceous grit — very friable — no fossils seen. 



15 feet. 



Alternations of lignite and clay. This bed is variable in thick- 

 ness, as well as in the proportions of the materials, at different 

 localities. 



Heavy-bedded gray and ferruginous friable sandstone, con- 

 40 feet. taining Melania Nebrascensis, Paludina muUilineaia, Bulimus Urn- 

 aeiformis, Corbula mactriformis, &c. &c. 



The bed Q of this section is here only seen at low stages of the river, and then 

 but a few feet of it is exposed above the water line. Near Long Lake, however 



[May, 



