with such volume, velocity, and load of mud, as to destroy for a time the oyster and fish industries of that locality.[71] [Illustration: PLATE XV. NEAR HAHNVILLE, LOUISIANA. U. S. Geol. Surv.] [Illustration: PLATE XVI. Fig. 1. MISSOURI. U. S. Geol. Surv. Fig. 2. MISSOURI. U. S. Geol. Surv. Fig. 3. MISSOURI. U. S. Geol. Surv.] [Illustration: +Fig.+ 179.—Flood-plain of the Mississippi River south of the mouth of the Ohio. (From charts of the Miss. Riv. Commission.)] [Illustration: +Fig.+ 180.—Diagram illustrating an early stage in the development of meanders. The shaded part represents the area over which the stream has worked.] =Flood-plain meanders. Cut-and-fill.=—A stream with an alluvial plain is likely to meander widely (Pl. XVI). In general terms this may be said to be the result of low velocity, which allows it to be easily turned aside. Were the course of such a stream made straight, it would soon become crooked again. The manner of change is illustrated by Figs. 180 and 181. If the banks be less resistant at some points than at others, as is always the case, the stream will cut in at those points. If the configuration of the channel is such as to direct a current against a given point, _a_ (Fig. 180), the result is the same, even without inequality of material. Once a curve in the bank is started, it is increased by the current which is directed into it. Furthermore, as the current issues from the curve, it impinges against the opposite bank and develops a curve at that point. The water issuing from this curve develops another, and so on. Once started, the curves or meanders tend to become more and more pronounced (compare Figs. 180 and 181). In the case represented by Fig. 1, Plate XVI (Missouri River near Brunswick, Mo.) the narrow neck of land between curves is almost cut through. When this is accomplished, the stream will abandon its wide curve. A later stage in the process is shown in Fig. 2, Plate XVI (the Osage River near Schell, Mo.).