Page:A Brief History of the Indian Peoples.djvu/28

24 the Indian plains, we must have a clear idea of the part played by these great rivers ; for the rivers first create the land, then fertilize it, and finally distribute its produce. The plains were in many parts upheaved by volcanic forces, or deposited in an aqueous era, long before man appeared on the earth. But in other parts the plains of Northern India have been formed out of the silt which the rivers bring down from the mountains, and at this day we may stand by and watch the ancient, silent process of land-making go on. A great Bengal river like the Ganges has two distinct stages in its career from the Himalayas to the sea. In the first stage of its course, it runs along the bottom of valleys, receives the drainage and mud of the country on both sides, absorbs tributaries, and rushes forward with an ever- increasing volume of water and silt. But by the time that the Ganges reaches the middle of Lower Bengal, it enters on the second stage of its life. Finding its speed checked by the equal level of the plains, it splits out into several channels, like a jet of water suddenly obstructed by the finger, or a jar of liquid dashed on the floor. Each of the new streams thus created throws off its own set of channels to left and right.

The Bengal Delta.–The country which these numerous channels or offshoots enclose and intersect, forms the Delta of Bengal. The network of streams struggles slowly across this vast fiat; and the currents are no longer able, owing to their diminished speed, to carry along the silt or sand which the more rapid parent river had brought down from Northern India. The sluggish split-up rivers of the delta accordingly drop their burden of silt in their channels or on their margins, producing almond-shaped islands, and by degrees raising their beds above the surrounding plains. In this way the rivers of a delta build themselves up, as it were, into high-level canals, which in the rainy season overflow their banks, and leave their silt upon the low country on either side. Thousands of square miles in Lower Bengal thus receive each autumn a top-dressing of new soil, brought free of cost by the river-currents from the distant Himalayas, — a system of natural manuring which yields a constant succession of rich crops.

The Rivers as Land-makers.–As the rivers creep further