Vig. 4. 
Abandoned bends at high levels show tht the stveam has been mean- 
dering for a long period. The fact that it no longer overflows its valley 
floor, but only the channel floor, means that it is slightly intrenched, is 
making a new flood plain at a lower level, as the cross profile shows 
(Fig. 2), and leaving its fermer flood plain as a terrace. In intrenched 
meanders cut-offs are rare, because they occur only where a neck is cut 
through by lateral erosion. The cut-offs of Normal brook are made in 
this way and not by overflow across a neck. In such cases the meander 
belt has no self-limiting width, but is restrained only by the bluffs. In 
Normal brook the width of the beit is about thirty times the width of the 
low water stream and not more than five times the average width of the 
high water channel. The present base level for the brook is the surface 
of the gravel terrace in the Wabash valley. The brook once emptied di- 
rectly into the river when it stood at a level ten or fifteen feet above the 
terrace. Therefore the brook has been subjected in post-glacial times to 
a fall of base level of that amount. Meanders acquired during a condition 
of higher base level and gentler slope may have been inherited and mod- 
erately intrenched by the present stream. 
