DAVIS: RIVER TERRACES IN NEW ENGLAND. 301 
more definite proof of this feature in the behavior of a meandering river 
is found in the new edition (1900) of the Preliminary Map of the Mis- 
sissippi (one inch to a mile), in which a red overprint indicates the new — 
position of the channel, as determined some fifteen years after the 
previous survey (see especially sheets 14, 16, and 18). 
The same down-valley shifting of the meanders is seen in the enclosed 
meanders of many rivers, typified in North branch of the Susquehanna, 
Figure 8. This fine river has in- 
A LSS: 
rN \ 
FD A a NS 
TUE : 
cised its course beneath the up- 
lands of northern Pennsylvania. 
The upland spurs that enter the 
river curves have been subjected 
on their up-valley sides to a per- 
sistent sweeping that is but little 
less effective than that by which 
the curved re-entrants between Ll ML 
the spurs have been scoured out. Uj ee 
The up-valley side of the spurs yy, mn 
have strong bluffs, as different ee ZZ Be | 
from their gentle down - valley 
slopes as are the high lateral 
bluffs that enclose the curves “Fie. 8. 
from the gentle terminal slopes of 
the spurs. Itis noteworthy that in this case of a rock-walled valley, the 
down-valley shifting of the curves does not seem to have been more 
than fifteen or twenty times greater than the degrading of the river 
channel in the latest period of valley trenching ; while in the case of 
terracing streams in drift-filled valleys, the first of these changes ex- 
ceeds the second in a much higher degree. It may be further noted 
that the North branch of the Susquehanna above Wilkes Barre seems 
for some time past to have ceased deepening its valley, for narrow 
double-curved scrolls of flood plain are now systematically added to the 
outer end and the down-valley side of the spurs, as may be especially 
well seen just above Tunkhannock, and as is indicated ‘by the dotted 
areas M M’, opposite the under-cut bluffs, N N’, Figure 8. 
Other examples of meandering valleys, exhibiting the systematic lateral 
growth and down-valley shifting of the meander curves, might be 
instanced ; a few of them are mentioned in my paper on the Drainage of 
Cuestas (89). It is my hope to give at another time a fuller account 
of this phase of river development, and then to show how satisfactorily 
