DAVIS : RIVER TERRACES IN NEW ENGLAND. 335 



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 beeu 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 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 



