FORMING THE BAD LANDS OF JUDITH RIVER. WT 
above the water level of the Missouri, near the mouth of Little Rocky Mountain Creek, 
which, from its lithological character and position, we have hitherto considered as belong- 
ing to Formation No. 1. It first makes its appearance as a seam of carbonaceous grit, of 
a dull reddish colour, very light and loose, like ashes, about one foot in thickness, separating ~ 
No. 4 from a bed of sandstone beneath. As we ascend the river, a bed of sandstone rises 
rapidly above the water level, very variable in its lithological character. It is a yellowish 
gray friable sandstone, with small concretions of iron in yellow seams, layers of fine 
grained compact rock, turning reddish brown on exposure, also gray coarse grained con- 
cretions of sandstone. No fossils were found at this point, though some local seams of 
lignite occur, from one to two inches in thickness. Just below Ammel’s Island, is an ex- 
cellent exhibition of lignite and sand bed. The dip toward the south-east is at least ten 
feet to the mile. 
Section of Beds in Descending Order. 
1.—Cretaceous Formation, No. 4, with its usual lithological characters and a great pro- 
fusion of fossils, Ammonites, Baculites, Inoceramus, Ostrea, ce. 
2.—Lienite. Ist. Dark gritty shale, 4 inches. 2d. Excellent coal, bituminous, very 
hard, of a jet black colour, 1 inch. 3d. Coarse gritty lignite with small seams of carbon 
disseminated through it, which have a somewhat crystalline appearance, also considerable 
selenite in crystals, 5 inches. 
3.—A variable sandstone, generally gray or ash-coloured, coarse grained and friable, 
with compact fine grained concretions. But throughout the bed are streaks or seams of 
ferruginous sand, some small globular masses of oxide of iron, and occasionally a local seam 
of lignite one or two inches in thickness, 50 to 80 feet. 
About five miles above Ammel’s Island, on the left bank of the Missouri, we have the 
following section descending : 
1.—Cretaceous Formation, No. 4, capping the hills. 
2.—Ist. A seam of lignite, 10 inches. 2d. Stratum of clay, 15 inches. 3d. Earthy 
lignite, 12 inches. 
3.—Grayish brown ferruginous sandstone, containing numerous fossil mollusca of unde- 
scribed species, 60 to 80 feet.* 
4.—A bed of earthy lignite, rising just above the water’s edge, 2 feet. 
A little farther up the river, the lower bed of lignite becomes three feet in thickness, and 
of a purer quality. The bed of sandstone varies from 80 to 100 feet in thickness. Where 
No. | first appears near the mouth of Little Rocky Mountain Creek, the upper seam of 
lignite separates No. 4 from the bed of sandstone. Fifty miles farther up the river, the 
same lignite bed is overlaid by 40 to 60 feet of ferruginous arenaceous clays with concre- 
* Nearly all the fossils collected from this bed were unfortunately lost. 
