Annual report ..[bulletins and circulars] . which later are built itito the flood-plains. onward, perhaps to a lake, which it commences to fill, forming abroad delta of level and fertile land, near where the stream entersthe lake. Or, possibly, the stream enters the sea and builds adelta there, as the Mississippi river has done. But much of the mud does not reach the sea. The greatestsupply comes when the streams are so flooded by heavy rains ormelting snows, that the river channel is no longer able to hold the 40 the water, which then rises above the banks, overflowing the sur-rounding countr
Annual report ..[bulletins and circulars] . which later are built itito the flood-plains. onward, perhaps to a lake, which it commences to fill, forming abroad delta of level and fertile land, near where the stream entersthe lake. Or, possibly, the stream enters the sea and builds adelta there, as the Mississippi river has done. But much of the mud does not reach the sea. The greatestsupply comes when the streams are so flooded by heavy rains ormelting snows, that the river channel is no longer able to hold the 40 the water, which then rises above the banks, overflowing the sur-rounding country. Then, since its current is checked where itis so shallow, the water drops some of its load of rock bits onthe flood-plain, much as the muddy water in a gutter drops sandor mud on the sidewalk when, in time of heavy rains, it over-flows the sidewalk. Many of the most fertile lands of the world are flood-plains ofthis kind, where sediment, gathered by the streams farther uptheir courses, is dropped upon the flood-plains, enriching them by. 17.—Near view of a cut in glacial soil, gullied by the rains, and with7iuynerous transported pebbles embedded in the rock flour. new layers of fertile soil. One does not need to go to the Nile,the Yellow or the Mississippi for illustrations of this ; theyabound on every hand and many thousands of illustrations,great and small, may be found in the State of New you can find one. There are other ways in which soils may be formed (Fig. 17) ;but only one more will be considered, and that is the way in whichmost of the soils of New York have been made. To studv this 41
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherithac, bookyear1899
