At St. Paul the navigable stage of the river practically begins, although there is more or less navigable water above the falls at certain seasons. From St. Paul to Cairo the river flows between bluffs, the terraces of Champlain times, from ten to fifty miles apart. Between the bluffs are the bottom lands, often coincident with the flood plain, along which the river channel wanders in a devious course of 1,100 miles. The soil of the bottom lands is, of course, alluvial, and was deposited by the river during past ages; that beyond the bluffs is a part of the great intermontane plain, and is sedentary--that is, it has not been materially disturbed since the plain was raised above the sea level by the uplift of the continent. From Cairo, at the junction of the Ohio River, the plain to the southward is nearly all made land, and in a few spots only does the river touch soil which it has not itself made. Here the Lower Mississippi proper begins, and here, at some not far distant time in the past,[2] was the head of the Gulf of Mexico. A fuller description of the Lower Mississippi is unnecessary here, inasmuch as the following pages are mainly devoted to this part alone. [Footnote 2: Estimated at from 100,000 to 150,000 years. Such estimates, however, are but little better than guesses.] HISTORICAL. Nearly three and a half centuries have elapsed since De Soto, that prince among explorers, traversed the broad prairies that lie between the border highlands of the Western continent, and beheld the stream which watered the future empire of the world. His chroniclers tell us that he was raised to an upright position, so that he could catch a fleeting glimpse of the restless, turbulent flood; for even then the hand of death was upon him, and soon its waters were to enshroud his mortal remains. "His soldiers," says Bancroft, "pronounced his eulogy by grieving for their loss, and the priests chanted over his body the first requiems ever heard on the Mississippi. To conceal his death, his body was wrapped in a mantle, and, in the stillness of midnight, was silently sunk in the middle of the stream." Just across the river the Arkansas was pouring in its tumultuous flood, and its confluence was the site of the future town of Napoleon, which in coming years was to be historic ground.