36 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
ping terraces, and not the absence of them, which arouses interest. 
The Whetstone Brook at its junction with the Connecticut River at 
Brattleboro, is a vigorous, active stream, swinging within a compara¬ 
tively narrow, rock-bound valley. In its swinging and degrading, the 
brook has uncovered ledges at each lower level, thus successively 
narrowing the width of its wandering belt. Consequently a most 
excellent example of stepping terraces occurs, being of sufficient width 
to allow the construction of a street and its houses with cross-roads 
ascending the terrace scarps. This topography is recognized as a 
unique feature of the town. 
The distribution of high and low scarp terraces as typically developed 
Fig. K.— Distribution of high-scarp and low-scarp terraces as controlled and 
defended by rock ledges. 
is illustrated by text-figure K. Assume that a low-scarp terrace is 
first formed along one border of the belt of wandering. After a few 
swings, a ledge is discovered, consequently all the terraces of earlier 
swings lying back of this ledge are preserved. Every later swing of 
the river is checked nearer and nearer the axis of the valley, because 
of the sloping surface of the buried rock ridge. A flight of stepping 
terraces is formed as a result of the defended cusps. Down-stream 
