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5. 
Mesozoic and Cenozoic Geology and Paleontology.. 193 
Ist. “Blue hard pan,’ resting unconformably on the surface of 
the stratified rocks. This is a very compact mass of blue clay, marl 
and sand, inciuding great numbers of small, partially water-worn, 
crushed and striated pebbles, principally fragments of: blue limestone 
and primitive rocks. It contains lime, so much as to effervesce with 
acids, and to hasten vegetation when applied to land. Beside its strong 
blue color, it is characterized by imbedded timber, dirt beds, leaves, 
sticks, and what are called by well diggers “‘ grape vines.’? It is so 
solid as to be almost impervious to water, and is very difficult to ex- 
cavate. 
2d. “Yellow hard pan,” resting unconformably on the stratified 
rocks, and the “blue hard pan.” This is a compact material, of a 
dull yeilow color, with fewer stony fragments or pebbles, and less cal- 
careous and more aluminous matter than the blue hard pan. It is not 
quite as solid as the blue, more pervious to water, and contains more 
and larger pieces of primitive rocks. The clays of the country, used 
for bricks are principally of this bed. It forms a hard, stiff soil, 
adapted for grass. The flat regions and savannas of the northwest 
quarter of the State, are caused by the surface presence of this bed. 
3d. “Sand and gravel drift,” containing granite bowlders (in small 
numbers ), of large size, and unconformable to Nos. 1 and 2, and the 
other rocks. It exhibits little regularity of stratification, is composed 
of inferior patches of coarse sand and gravel, intermingled at all in- 
clinations, evidently the result of long continued and vigorous action 
of water in rapid motion. The gravel’is coarse, but much worn, 
rounded and smooth, like the gravel beds of rapid streams. The por- 
tion of earthy matter is about one half, of a reddish and yellowish col- 
or, showing the presence of oxide of iron, and containing various pro- 
portions of sand and clay. Almost every rock in the northern part 
of America is represented in the gravel; but the greatest part by far 
is from the underlying and adjacent strata. There are pebbles of 
quartz, trap, granite, gneiss, conglomerate, limestones of all ages, iron 
ore, slate, coal and sandstone. In this there has been found timber 
but very rarely. 
4th. The “ valley drift,” eee principally of debris of the ad- 
jacent rocks, and occupying the lower parts of the great valleys of drain- 
age. It is more gravelly and less earthy, and the gravel is more of 
local origin than in No. 3, while the beds of sand are less common. It 
is in the “ valley drift” or swamp mud that the bones of the mastodon 
and other large animals are usually found. 
