DAVIS: RIVER TERRACES IN NEW ENGLAND. 30D 
has swung against the steep face of these ledges, sweeping them prac- 
tically free from drift on the up-valley side down to modern flood- 
plain level, but fine flights of stepping terraces are preserved on the 
down-valley side of each ledge, where the trailing remnants of suc- 
cessive flood plains have been defended from stream attack. At least 
ten different terrace levels can be counted adjoining ledge M. The 
third and fourth levels from the top are pleasantly shaded by a pine 
grove, and are used as a picnic ground, access to which is conveniently 
given by an electric railroad on the valley floor. Some of these 
terraces may have been carved by a small stream that here enters 
from the north, but in any case they have all been developed with 
respect to graded flood plains of the main stream. Their vertical 
interval ranges from five to ten feet, which may be taken here, as in 
other cases, to represent the amount of deepening that the valley floor 
suffered between two northward swings of the stream. The value of 
the ledges is most manifest ; they defended the upper terraces from being 
consumed when the lower terraces were cut by the returning stream. 
Ledges Q and R present similar features in flights of eight and six 
steps respectively. The river is to-day swinging vigorously against the 
base of ledge M. The modern flood plain reaches the base of Q and R, 
and is opened northward between M and Q in a space that seems to be 
comparatively free from ledges. The ledges here outcropping on a low 
terrace at N and O seem to have served the double purpose of stopping 
the northward swinging of the main stream, and of limiting the east 
and west swinging of the side stream at that level. I have not closely 
examined the terraces up-valley from M, but at least one of the blunt 
cusps there seems, when seen from the terrace on the opposite side of 
the valley, to be defended by a ledge at present flood-plain level. Down- 
valley from R, the valley side is heavily wooded for quarter of a mile. 
Then it closes in as numerous ledges and boulders make their appear- 
ance about S, near the main road bridge. 
Low-scarp terraces are wanting at high levels on the south side of the 
valley. The upper plain descends by a single strong scarp, twenty feet 
or more in height. It presents a number of sweeping re-entrants 
between the defended cusps, A, B, C, D, and E. The A-B re-entrant is 
floored by a rather uneven plain in which several indistinct terraces have 
been cut on what seems to be at least in part a mass of till, for large 
boulders are seen thereabout ; and this plain is cut off in front by two 
terraces, whose blunt cusps from F to G appear to be in part determined 
by ledges, in part by boulders. The small tributary stream that crosses 
