340 M . JEFFERSOK LATERAL EROSIOX 0^' MICHIGAN RIVERS 



signs of slipiDing that was not counted. The count extended 16% miles 

 along the river, to a point about 3 miles east of Plymouth, all on the 

 ancient lake floor. 



Pacings made by Mr Davis and the author in October, 1905. The 

 scaurs on the right average 39 paces long; on the left, 37. On the right 

 there are hot quite two to a mile; on the left, one to two miles. For one 

 space of four miles there were no scaurs on the left. Though the pro- 

 portion of scaur is about the same here as on the lower Eouge, there is 

 much irregularity in its distribution. The way the river keeps to the 

 right, even when not making scaur, is shown fairly typically on the 

 sketch here. 



It has the same tendency to the right side of the valley, even in that 

 part of the upper valley where scaurs preponderate on the left (41 per 

 cent of all on the right). The shortening of the scaurs goes well with 

 their lessened frequency, their lesser total length, and the clearer water 

 of the stream. It is less actively widening its valley than the lower 

 Eouge. It does not hold less strongly to the right (south) side. 



North Branch of the Rouge 



This part, called on the map the Eouge, is deeply cut into its plain — 

 more than 10 feet, we estimated, all along its course, and at times as 

 much as 15. It does not flood the whole of this plain, which is not, 

 therefore, a true flood-plain; yet there are points 15 feet above ordinary 

 water where deposits of sand had been left the previous spring, though 

 only in narrow strips. 



The writer has twice seen the lower Eouge cover its plain from blufE to 

 bluff — a thing that certainly never occurs on the North branch now. 

 For this reason this stream is not comparable to the others. It is not 

 widening its flood-plain. Although it was examined along a distance of 

 more than 20 miles, true scaurs were entirely wanting. One patch of 75 

 paces was mapped as scaur at a point where a tributary gully joins the 

 main stream in a long stretch of what may be called "dead" scaur, en- 

 livened here by the cutting of the tributary. By "dead" scaur is meant 

 bluff descending steeply from the upland to the flood-plain of a river, 

 with cracks in the ground, landslips, and trees tipping out of the vertical, 

 though the whole face is fairly well grassed and not a continuous slope 

 of bare earth like the true scaur. Attention has been called to this sort 

 of thing in describing the middle Eouge. What was counted for scaur 

 there was admittedly different froni the scaurs of the lower Eouge, but it 

 was all fairly active. On the North branch everything was noted that 



