DAVIS: EIVER TERRACES IN NEW ENGLAND. 303 



belt as a whole and the more local shifting of an irregularly sweeping 

 meander. The compound movement of sweeping meanders in a swinging 

 meander belt will be called wandering, this term being fully justified 

 when it is noted that many unsystematic irregularities must be devel- 

 oped in a stream channel, whereby it will depart significantly from the 

 simple and regular movements here considered. The whole breadth of 

 the valley floor that may be worn down by the stream will be called the 

 belt of wandering; this corresponds to many of our flood plains or 

 " intervals." 



In an ideal case, a regularly growing pattern of meander curves might 

 be imagined slowly sweeping down a valley, the meander belt collapsing 

 here and there, now and then, but growing again to its ordinary breadth 

 as new curves are developed in the place of the old ones. At any point 

 in the valley, an endless procession of meanders would sweep past. 



If it be now supposed that the wandering stream is slowly degrading 

 its valley floor, each meander will sweep past a given point at a slightly 

 lower level than that of its predecessor ; and each time the meander 

 belt swings across the valley from one side to the other and back again, 

 it will return at a distinctly lower level than that at which it left. The 

 flood plains formed at different stages of this leisurely pi'ocess will differ 

 in altitude, and all of them will be inclined gently down the valley. It 

 is the remnants of these flood plains that form our terrace plains. 



Ideal Terrace Patterns : Early Stage. Soon after the stage of 

 degradation has been definitely established and the meandering stream 

 begins to swing across the valley at a little lower level than before, a 

 condition represented in Figure 9 may be reached. In this figure, as in 

 a number that follow, it is supposed that the view is taken from a 

 considerable height, looking northwest across the valley of a south-flow- 

 ing river. The terrace plains are left blank in most of the diagrams. 

 The western meander in the foreground of Figure 9 is now scouring out 

 a curve in a low concave terrace scarp, B, the ninth of its kind within the 

 limits of the diagram. A small portion of a terrace, A, of slightly less 

 height, is shown in the immediate foreground ; it may represent the work 

 of the preceding westward meander, while the next following westward 

 meander is cutting out a deeper terrace, C, in the background. Terrace 

 A may be taken as one of the first marks made by the degrading stream. 

 Terrace B is of greater height than A, because A has been under-cut and 

 consumed in the production of B, except in the immediate foreground. 

 Terrace C is as yet independent of B, and therefore shows a height to be 

 measured only by the few inches or feet of depth to which one sweeping 



