10 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
within a limited area, as the river in its wandering and degrading 
discovered a large number of rock ledges which defend the higher 
and older terraces and prevent their erosion. 
In consideration of the variety of terrace forms developed by the 
West River, it seemed advisable to survey with transit and stadia an 
area covering about two square miles at the junction of the West and 
Connecticut Rivers. The area surveyed was plotted on the scale of 
four hundred feet to the inch. Terrace scarps have been hachured 
and the different levels of the plains noted by heights (in feet) above 
mean sea level, and in groups by shading. The map (pi. 1) reveals 
the destructive postglacial work of the West River in the constructive 
postglacial filling of its valley. 
Another portion of the field work has been the measuring, with- a 
Locke level, of terrace scarps here and there (at frequent distances) 
for about two hundred miles along the Connecticut River from Say- 
brook to Brattleboro. From such measurements taken in different 
sections of the valley, it may be possible to determine by means of their 
variations whether an even regional uplift or a tilting was chiefly 
responsible for the activity of the river in degrading its valley. Such 
dimensions will give direct proof as to the kind of movement by which 
the process of terracing was initiated, and will possibly confirm the 
evidence already at hand regarding the nature of postglacial move¬ 
ment in New England. The results of this portion of the field work 
will be presented at another time. 
For valuable suggestion and advice in this study the writer grate¬ 
fully acknowledges indebtedness to Prof. W. M. Davis, and also takes 
the present opportunity of thanking Dr. S. E. Lawton of Brattleboro, 
Vt., for unfailing kindness in the furtherance of the field work. 
Preliminary Inquiry. 
Terraces in the cycle .— A typical section of one of the terraced river 
valleys in New England (represented in the accompanying text-figure 
A) shows a broad rock valley, aggraded with drift, and partially de¬ 
graded by a swinging river checked in its lateral cutting here and there 
by the discovery of rock ledges. These ledges act as barriers against 
which the river is practically powerless. The river terraces are deposits 
of stratified sands and gravels temporarily delayed on their way to the 
