The river in several places expands to the width of many miles, embosoming numerous islands, some of which are broad and considerably extensive, and all of them covered with a growth of cotton-wood and willows. These are the only woodlands that make their appearance along the river, and in travelling westward these become less numerous and extensive, till at length they entirely disappear. Copses and skirts of woodland again present themselves in the neighbourhood of the mountains, but they are of small magnitude, and the trees they furnish are of a dwarfish growth. For a distance of nearly two hundred miles, commencing at the confluence of the North and South forks, and extending westwardly towards the mountains, the country is almost entirely destitute of woodland, scarcely a tree, bush, or even a shrub, making its appearance. {228} The Platte is seldom navigable, except for skin canoes, requiring but a moderate depth of water, and for these only when a freshet prevails in the river. No attempts have ever been made to ascend the river in canoes for any great distance; the prevalence of shoals, and the rapidity of the current, discouraging such an undertaking. The bed of the Platte is seldom depressed more than six or eight feet below the surface of the bottoms, and in many places even less; and spreads to such a width, that the highest freshets pass off without inundating the bottoms, except in their lowest parts; the rise of the water, on such occasions, being no more than five or six feet. In order to account in some measure for the diversity of soil observable in the vallies of most of our western rivers, it may not be improper in this place to assign one of the principal causes that operate in producing this effect. The alluvial deposits of which the river bottoms are formed, consist of particles of mud and sand, more or less minute. The coarser and more ponderous particles are of course soonest deposited, while the finer are transported by the current to a greater distance, and deposited near the mouths of the rivers. Thus it happens, that the bottoms situated nearest to the sources of the western rivers, are sandy, and contain but a small proportion of vegetable mould, while those nearer their mouths are generally furnished with a rich and fertile loam.