OF THE UPPER MISSOURI. 9 
in impressions of dicotyledonous leaves. The following section of the beds in descending 
order is exposed at this point: 
1. Yellow marl, recent. 10 to 15 feet. 
2. Yellowish and light gray, fine indurated grit, recent. 10 to 15 feet. 
3. A reddish friable sandstone, passing down into a very tough compact silicious rock of a greenish gray color. 
The whole bed fully charged with vegetable impressions, quite well preserved. 10 to 20 feet. 
4. Forty feet slope. The rocks though not exposed at this point are evidently formed of more friable sandstone, 
as is shown by the perpendicular bluffs cut by the river, three miles above, also at Wood’s Bluffs, near Decatur. 
The more compact silicious rock has been quarried during the winter and spring, and 
used in constructing a fine three-story building for the Omaha Mission, and it was found 
to serve an excellent purpose. ‘The whole bed at this locality seems to be filled with im- 
pressions of leaves, mostly of dicotyledonous trees, some of them closely allied to our 
recent oaks, willows, &c., with many forms not represented among living species. Frag- 
ments of silicified wood abound with globular masses of the sulphuret of iron. 
Fig. 3. 
nas 
The bluffs of sandstone near this locality often present the appearance shown by Fig. 3. 
The whole surface being covered with projecting seams of iron, the more yielding arena- 
ceous material being eroded, giving to the face of the bluff a very rugged aspect. 
After stopping at Blackbird Hill three days enjoying the hospitality of Dr. Sturgis, 
the gentlemanly superintendent of the Mission, I pursued my course along the banks of 
the river toward the Big Sioux, about forty miles distant. The red sandstone No. 1 is 
the principal rock in that region, but upon the sandstone I often found layers of rather 
VOL. XI1.—2 
