1876.] The Little Missouri “ Bad Lands.” 211 
layer is generally of a whitish or grayish color, and is made up 
largely of hard, semi-vitreous, vesicular material, the larger inter- 
stices of which are filled with ashy or earthy matter, while occa- 
sionally portions are so soft as to be easily crumbled in the hand, 
or crushed under the foot. Indeed, it is not much unlike the re- 
siduum left in our grates from the burning of common coal. 
The material next above this often shows signs of having been 
in a semi-molten or at least plastic condition, and generally pre- 
sents a great variety of tints, as olive, drab, yellow, gray, white, 
brown of various shades, purple, and even black. The purple 
and olive tints are quite frequent; the other colors often occur in 
harrow zones or mere lines, producing a very beautiful effect. 
The texture varies from a dense, compact, jaspery character to 
that so porous and vesicular that the mass will float upon water, 
with every degree of porosity between these extremes. This 
variegated layer is usually but a few inches in thickness, and is 
of rather local occurrence, as is also the scoriaceous or vesicular 
matter, neither appearing except where the heat has been very 
Intense. The scoriaceous material also varies greatly in color, 
being usually black, but sometimes grayish, while it also occurs 
of every shade of red, from dark reddish-brown’ to bright car- 
mine. These materials always pass gradually into the overlying 
reddened, baked clays, which, as previously stated, may vary in 
thickness from a few feet to twenty or more, and which, from 
their great thickness, bright color, and wide distribution, form 
one of the characteristic features of the region we are considering. 
The color of these beds is that of bright red bricks, and where 
the material has been thinly scattered about by the gradual dem- 
olition of buttes once covered by it, as sometimes happens, the 
resemblance of the locality to an old, long-abandoned brickyard is 
very striking. These hardened clays still retain the abundant 
impressions of plant-remains, but they are generally too frag- 
mentary to be of much value as specimens. A few quite well- 
Preserved casts of the leaves of exogenous plants occur, but the 
vegetable relics consist mainly of the imprints of broad-leaved 
Stasses and sedges, which seem to have in places nearly filled the 
clays, Heavy clay deposits almost always immediately overlie 
the beds of lignite, and when they are very heavy, or the seam 
of lignite is very thin, the metamorphism scarcely extends be- 
yond the stratum of clay ; usually, however, it affects the stratum 
of sand that rests upon the clay, sometimes converting it into a 
red, coarse-grained, rather soft sandstone, hand-specimens of 
