raphy and soil-constitution of the Illinois prairies points to a different and a peculiar history. Moreover, trees occupy the drier knolls of the prairies in the midst of the common atmospheric conditions.

Exactly the reverse of this theory is that which attributes the absence of trees to an excess of moisture in the soil at certain seasons. But we well know that there is no soil or situation so wet and stagnant but certain trees will flourish upon it-the willow, the cottonwood, the beech, the black ash, the alder, the cypress, the tupelo, the wateroak, the tamarack, the American arbor-vitæ, or some other tree-some of them standing joyously half the year, if need be, in stagnant water. Many swales are indeed treeless; but is this in consequence of the inability of a willow to take root and maintain itself, or rather in consequence of the formation of the swale in times so recent that the germs of trees have not yet been scattered over it? Moreover, wetness can not be attributed to many portions of the Illinois prairies which are entirely treeless. Is there a different cause for treelessness here?

Lastly, it has been suggested within a few years, by high geological authority, that the lack of trees is caused by excessive fineness of the prairie soil. It can scarcely be denied, however, that other soils, as pulverulent as that of the prairies, are densely covered with forest vegetation, and that in the same latitudes and under the same meteorological conditions. On the other hand, certain soils of a coarser texture are equally treeless. But the final objection to this theory, and to all theories which look to the physical or chemical condition of the soil, or even to climatic peculiarities, for an explanation of the treeless character of the upland prairies of the Mississippi Valley, is discovered in the fact that trees will grow on them when once introduced-not water-loving trees exclusively, but ever

>

greens, deciduous forest-trees, and fruit-trees, such as flourish in all the arable and habitable portions of our country. Every one will now admit that trees flourish upon the prairies. In proof of the fact, the prairie farmers are actively engaged in their introduction. "The prairies ***" says Gerhard,*"may be easily converted into wooded land by destroying with the plow the tough sward which has formed itself on them. There are large tracts of country where, a number of years ago, the farmers mowed their hay, that are now covered with a forest of young, rapidlygrowing timber. *** A resident of Adams County testifies to the effect that locust-trees planted, or, rather, sown on prairie land near Quincy, attained in four years a height of twenty-five feet, and their trunks a diameter of from four to five inches. *** In like manner, the uplands of St. Louis County, Missouri, which were in 1823 principally prairie lands, are now covered with a growth of fine and thrifty timber, so that it would be difficult to find an acre of prairie in the county." This testimony is confirmed by numbers of persons from various parts of the state whom I have questioned on the subject. The introduction of timber as a branch of rural industry is now systematically pursued. The principal drawback to the cultivation of forests and fruit-trees is the violence of the prairie winds and the occasional severity of the wintry weather.

If what I have suggested in reference to the persistent vitality of buried vegetable germs be true, we have a ready, simple, and beautiful solution of this long-vexed problem.

There are pretty satisfactory evidences that the soil of the prairies is of lacustrine origin. It has the fineness, color,

* Illinois as it Is, p. 277. Compare also Wells's Amer. Jour. Sci. and Arts, i., 331; Engelmann, Ibid. [2], xxxvi., 389; Edwards's Rept. Dept. of Agric., 1862, p. 495.

and vegetable constituents of a soil-accumulated upon a lake-bottom. We find in it, moreover, abundant fossil remains of a lacustrine character. Fresh-water shells of species still existing in Lake Michigan are found in localities many miles from the existing shore. Finally, we have found all around the chain of the great lakes abundant proofs that their waters once occupied a much higher level than at present. We have discovered the obstacle which dammed the waters to this extraordinary height. In short, we have ascertained that the prairie region of Illinois must have been a long time inundated, whether such inundation contributed to the characteristics of the prairies or not. I think it did. If I ascertain that the cause for an inundation exists; if I see the traces of an inundation all the way from Niagara River to Illinois; if the barrier which shuts out Illinois from the lake is not one third the height of the ancient lake-flood; if I find throughout the region exposed to inundation the peculiar soil deposited by fresh waters, together with traces of lacustrine animals which never wander over land, do I not discover a chain of facts which necessitates my conclusion? During the flood-tide of the lakes, Lake Michigan must have found an outlet toward the south. We find corroboration of this. The broad, and deep, and bluff-lined valley of the Illinois River was never excavated by the present inconsiderable stream. The deserted river valley discoverable at intervals farther north, indicates the former southward flow of a large volume of water. At Lemont this valley is distinct, with its bounding bluffs, and its "pot-holes" worn in the solid rock of the ancient river-bed. This was the work of the lake in its declining stages. At the earlier period, when the waters of Lake Michigan stood one or two hundred feet above their present level, how much of the region. south and west of Chicago must have been submerged?

The ancient lake must have reached its arms into Iowa,
Northern Indiana, and Southwestern Michigan.

While the expanse of lacustrine waters was brooding
over the region destined to become a prairie, they busied
themselves in strewing over the tombs of pre-glacial germs
a bed of mud which should forever prevent a resurrec-
tion. Lake sediments themselves inclose no living germs.
You will see the seeds of grasses and the fruits of trees,
washed in by the recent storm, floating upon the surface,
and eventually drifting to the lee-shore. If they ever sink
to the bottom, and wrap themselves in the accumulating
mud, it is after they have lost their vitality. Sunken and
buried, they go to decay. Let a lake be drained, and the
bottom remains a naked, barren, parching, shrinking waste.
No herbs, or grasses, or trees burst up through the pottery-
like surface. But every where, from beds of ancient gla-
cial materials, vegetation is bursting forth and announcing
itself. Lo, here I am! speaks the nodding young pine that
had been slumbering just beneath the surface through the
long and undisputed possession of the deciduous forest
which the axe has just mown down. Not so in a lake-
bottom. Here are the cerements of the dead, not the
wrappings of the slumbering.

When, therefore, the ancient lake relinquished dominion. over Central Illinois, he left a devastated and desolate country. Around the ancient shores of the abandoned area the emerald forest had stood nodding, and blossoming, and fruiting, while the inundating lake had washed the slopes down which the oaken and beechen roots descended to sip refreshing draughts. Ever since the time when the Atlantic and Pacific last held carnival in the Mississippi Valley, these vigorous trees had stood smiling upon the face of the freshening residuum left in Illinois on the final retreat of the oceans. A resurrected forest had

2

risen from the tombs of the preceding epoch. And not alone around the borders of the widened lake, but upon every island knoll which raised its head above the denuding waters. This encircling forest and these isolated island clumps still stood and flourished when at length the lake receded.

No turf carpeted the abandoned lake-bottom. No oak, or beech, or pine raised its head through the covering of lake-slime which separated the slumbering-place of vegetable germs from the animating influence of sun and air. By degrees, however, the floods, washed down the seeds of grasses and herbs upon the desert area, and humbler forms of vegetation crept from the borders toward the centre. At length the entire area smiled with vernal flowers, and browned in the frosty blasts of winter. The bulky acorn, and walnut, and hickory-nut traveled with less facility, and the forest more sluggishly encroached upon the lake's abandoned domain. In this stage of the history the Indian was here. For aught I know, he was here while yet the prairies were a lake-bottom. His canoe may have been paddled over the future spires of Bloomington and Springfield, and the muscalonge may have been pursued through the future streets of Chicago; but, at least, the Indian was present in the interval of time by which the herb distanced the tree in their race for possession of the new soil. In this interval he plied the firebrand in the brown sedges of autumn, and made for himself an Indian-summer sky, while he cleared his favorite hunting-ground of the rank growths which impeded both eye and foot. While the Indian was engaged in these pursuits, and while yet the forest had not had time to extend itself over the prairie, the white man came up the lake from Mackinac, crossed over the prairies. to the Mississippi, saw the Indian engaged in his burnings, and hastily concluded that this was the means by which