67 
river courses cutting here and there, through this into the 
Tertiary Formation of the ‘Bad Lands.” Thus the Cannon- 
ball near its mouth. Atthe camp on Heart River, mentioned 
above, specimens of marine shells were found, at an elevation 
not over 50 feet above the stream, still preserving their pearly 
appearance, but rapidly crumbling by exposure. In the 
creek-bed itself, a ledge of limestone with beautifully pre- 
served impressions of the leaves of dicotyledonous plants 
crops out, apparently unconformable and inclined at a steep 
angle, to the superincumbent formations. Between the Can- 
nonball and Heart Rivers, a very fine bed of apparently 
Basaltic Lava, black and full of cavities, covers the Plateau, 
whether above or below the Drift was not ascertained. This 
Lava Bed was the only exhibition of volcanic formations 
noticed on either of the two expeditions. It has the external 
appearance of a tolerably recent flow, the surface being piled 
near its margin with frothy blocks. The Takaokutah Moun- 
tains, whose ridge intersects the plain from east to west, 
about 70—90 miles (?) north of the camp on Heart River, and 
about due south of Fort Berthold, is composed entirely of a 
greyish green sandstone, which also covers the greater portion 
of the plateau between the Little Missouri and the Yellow- 
stone, and probably forms the masses of all the hills rising 
above the general level of the plateau. The formation of 
the hills and hillocks of the Little Missouri Bad Lands is 
highly peculiar. As seen from the edge of the plateau, the 
landscape is at once characterized by the singular shapes of 
the hills, whose summit flanks are often painted in red, 
yellow, blue, and other ochreous colors, and by a sharp black 
line, which goes through the entire view, like a knife-cut, and 
is due to a lignite bed. Other lignite beds crop out in the 
beds of the water-courses. Generally speaking, the body of 
the hills shows a bed of very friable sandstone, or rather of 
loose sand forming their base, to the rapid destruction of 
which the oft-recurring mushroom or glacier-table-like shapes 
are due. On this bed rest solid sandstones, which form the 
rim-base of the mushroom and the tops of the tables. Above 
this come formations not remembered, followed by a bed of 
