350 FRA NK B URSLE V TA YL OR 



of Berkshire county. Of course, the certainty of correlation and 

 reconstruction varies in different localities according as it is 

 necessary to use more or less interpolation. For example, across 

 Mount Washington the course of the ice-borders is almost 

 wholly interpolated. The few fragments of moraine found on 

 the mountain are so far from those in the surrounding valleys 

 that their connections must remain uncertain. These lines, how- 

 ever, are not drawn by mere guess, but as closely by rule as pos- 

 sible, and are projected from points of observation in the valleys 

 near by. The terminal deposits in the valleys on both sides of 

 the mountain are mostly well developed and form an excellent 

 basis for correlation. About the same amount of interpolation 

 was used on Greylock mountain. The lines across Hoosac moun- 

 tain are somewhat less certain, but they are based on excellent 

 data in the valleys on both sides. The Green mountains, the 

 northern part of the Taconic range, and the Rensselaer Grit 

 plateau have not yet been sufficiently studied for mapping. In 

 the rest of the area interpolation is used in less degree and is 

 generally simple, and reconstruction of the ice-fronts is corre- 

 spondingly easier. 



THE BECKET AND LENOXDALE MORAINES. 



Where ice-borders are represented by moraine fragments 

 scattered in such disorderly fashion, it is fortunate to find two 

 or three sections of some length in which the evidence for con- 

 tinuity is complete. Such sections establish the general trend 

 of the ice-border and form excellent bases for the correlation of 

 other less clearly connected fragments of near-by earlier and 

 later borders. The second moraine, as shown on Figs. 9 and 10, 

 is substantially continuous from Tolland to Colebrook, only a 

 very little interpolation being required to complete the line 

 between these places. There are a number of other sections of 

 similar length, the continuity of which is quite clear. But besides 

 these there are two longer sections, which in their combined 

 length reach entirely across the Housatonic quadrangle from 

 southwest to northeast. These are the Becket and Lenoxdale 

 moraines, parts of the sixth and eighth, as shown in Figs. 9 and 1 0. 



