. Elementary physical geography;. LOOPS AND CUT-OFFS OF THE LOWER MIS-SISSIPPI The abandoned channels jorm an intricate network oj pas-sages. THE WASTING OF THE LAND: RIVERS 115 channel decreases, the velocity of the current is checked,and because of the slackening current, the water is con-stantly dropping sediment. Islands are common in rivers carrying a considerablesediment. The anchoring of a snag, or any other obstacle,slackens the current and causes deposition of latter increases in amount until finally it reaches the. ISLANDS IN THE MISSISSIPPI RIVER surface. Then vegetatio
. Elementary physical geography;. LOOPS AND CUT-OFFS OF THE LOWER MIS-SISSIPPI The abandoned channels jorm an intricate network oj pas-sages. THE WASTING OF THE LAND: RIVERS 115 channel decreases, the velocity of the current is checked,and because of the slackening current, the water is con-stantly dropping sediment. Islands are common in rivers carrying a considerablesediment. The anchoring of a snag, or any other obstacle,slackens the current and causes deposition of latter increases in amount until finally it reaches the. ISLANDS IN THE MISSISSIPPI RIVER surface. Then vegetation takes root and an island timber may clog the channel. The roots of afloating tree catch on the bottom, forming a snag. Othertimber lodge upon it, and in time form a raft. Per-haps the latter may float down stream, but more likelyit forms a permanent obstruction. The famous Red Riverraft is many miles in extent. 116 PHYSICAL GEOGRAPHY The Formation of Loops.—The river which flows overa decreasing slope has a tendency to form loops or, ox-bows, in its lower course. In general, such loops arc longlived, but if there is a succession of years of high water,the conditions are changed. The volume of water is in-creased, the current is quickened, and the water begins topick up the sediment which it had dropped. In time, the neck of the loop is cut away,and the river shortens itschannel — sometimes bytwenty or thirty miles. Theline of moats, or oxbow lakes,along the lower Mississippimarks the old loops andabandoned
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