302 The Origin and Formation of Prairies. [ May, 
places strong currents have washed together coarse sands and 
gravels; in others, where the water has had a gentle movement, 
it has deposited only the finest sediment; the greater portion of 
the bottoms, however, consists, as we might expect, of a mixture 
of these materials, enriched by the humus from decaying vegeta- 
tion. There has been no lack of opportunities for the formation 
of swamps in these bottoms, which are frequently from four to 
eight miles or more in width. Nevertheless, on these bottom 
lands, formed to a great extent in the way described by Prof. 
Lesquereux, and much more recently than can be claimed for the 
higher prairies, we find the heaviest growth of timber and the 
greatest proportion of timber land. 
` In the southern part of the State, where upland prairies do not 
exist, the flood-plain is clothed with the densest growth of forest 
trees; and this almost irrespective of the character of the soil. In 
Alexander county, for instance, as stated in the Report of the 
Illinois State Geological Survey, “the bottom lands are generally 
flat and are interspersed with cypress ponds and marshes.” The 
higher bottoms are said to be heavily timbered with various kinds 
of trees. “The swampy lands are characterized by the growth 
of the cypress, sweet gum, tupelo gum, cottonwood, pecan, willow, 
etc.” We find analogous statements made concerning the coun- 
ties lying northward along the Mississippi, until we reached the 
region where prairies begin to appear on the highlands. Then 
small prairies appear also on the flood-plain ; but these are likely 
to occupy the higher grounds and the dense timber growth the 
low wet lands. We learn of heavy forests on soil described as a 
deep sandy loam, highly charged with humus; and on similar 
soils, bottom prairies. Nor is it unusual along the Mississipp! 
and other rivers of Illinois to find bottom prairies whose soil con- 
tains a large proportion of sand and gravel. In the report of the 
geology of Jo Daviess county, the most northern river county of 3 
the State, we find this statement: “In the western part of the 
township of Hanover, bottom timber-land, alluvial grass-land, and 
a table-land, high and dry, exhibit all the characteristics of the 
ordinary Mississippi alluvial bottoms. Farther down in Carroll 
county this bottom changes into the broad, well-known sand 
prairie, an old, broadly extended, glittering Mississippi sand-bar. 
Such quotations from many independent observers could be 
multiplied indefinitely to show: Ist. That even marshes may 
be timber-grown; 2d. That the distribution of forest lands bears 
