ACCORDING TO THE BEST AUTHORITIES.
[Click anywhere on chart for high resolution image.]
Rivers are supplied with water principally from springs, and the melting of snow upon high mountains. Mountains attract clouds around their tops and sides, and by this means become saturated with water, which, finding its way through the fissures of the rocks, forms springs. In this manner probably all springs are formed, whether they are found on mountains or plains. Heavy rains also augment the quantity of water, and often after a heavy fall of rain, many rivers are so swollen that the water overflows their banks, and the flood sweeps away every thing that is within its reach.
The Mississippi is subject to inundations during the spring, and the banks of the river being higher than the adjacent country, the water never returns to the river, but seeks other channels. These inundations greatly enrich the lands.
The banks or shores of rivers present very different appearances, according to the formation of the land through which they pass. The banks of some rivers are but little elevated above their level, and slope gently down to the water’s edge; others flow through rocky channels, and are walled on each side with high and almost perpendicular precipices.
PASSAIC FALLS, NEW JERSEY, U. S.
Sometimes a precipice occurs immediately across the course of a river, and the water falling nearly perpendicularly over, forms a cataract or falls.
They are often obstructed by rapids which render navigation difficult and sometimes impracticable. A rapid is a gradual descent in the bed of a river, where the current is swift, and the water shallow.