FISHER: RIVER TERRACES. 
31 
feet. The river must have been meandering in great loops, extending 
one meander far into the 280-foot terrace, then curving broadly to the 
other side of the meander belt and returning so as to make a more 
extensive cut into the same flood plain. The evidence of this is most 
clear. A rock barrier held the first meander mentioned, at its lower 
side, and prevented the cutting away of the long spur of the 280-foot 
flood plain. This necessarily deflected the river broadly to the 
western side, and returning, it cut the extensive bend, represented 
to-day by a distinct ox-bow channel, a course from which the river 
was withdrawn by a short-cut. It is interesting to note that the 
outer bank of this great meander bend is distinctly cuspate, which 
would seem to indicate that the current impinged with varying force 
upon the bank of erosion. On the sixth return (pi. 5, fig. 6), the 
river apparently cut to the 225-foot level, which produced a scarp of 
38 feet. This scarp is distinctly deeper than the other one-swing 
scarps of the valley. Presumably the same amount of time was nec¬ 
essary for the river to swing across its valley; therefore if the power 
for degrading remained the same, this scarp is not a one-swing but 
more probably a two- or a three-swing scarp. Evidence from the 
other side of the valley may tend to prove in the absence of inter¬ 
vening levels, whether this is a one- or more-swing scarp. The 
small terrace which appears at the northwestern end of this 225-foot 
level is so insignificant — only one or two feet above the 225-foot 
plain — that it is more probably a two-sweep terrace and does not 
indicate a swing of the river. On the seventh return (pi. 6, fig. 7) 
the river flowed at the back of the 209- to 214-foot level. Evidently 
as the river moved from this position, it swung strongly to the right, 
reaching the base of the Retreat scarp,— chiefly by the partition proc¬ 
ess. By short-cut, across the narrowing flood plain, the river was 
withdrawn to its present position on the left side, and is flowing now 
at the 200-foot level. This last short-cut disturbed the adjustment 
of the current, deflecting it to the right and causing the formation 
of the large island at the 205-foot level. 
The form and position of the 291-foot cusps (pi. 4, fig. 4) are acci¬ 
dental, carved by the intersection of two lines having no particular 
relation to each other. All the elements of these cusps are vari¬ 
able, influenced in some other way than by a common control. They 
may be considered typical cusps formed by an unguided, swinging 
river. A definite arrangement and grouping of cusps is recognizable 
