RECESSIONAL ICE BORDERS IN BERKSHIRE, MASS. 329 



GENERAL RELATIONS OF THE RETREATING ICE-FRONT TO THE 

 LARGER LAND RELIEFS. 



It is interesting to note the general relations of the larger 

 features of the land relief to the receding ice-front; for, accord- 

 ing as the ice-front retreated across them in one direction or 

 another, the recessional history of the region was one thing or 

 another very different thing. The earlier investigators found 

 that the general direction of ice-movement was about S. 30° to 

 40° E. It is a general principle that the direction of ice-move- 

 ment at any point near the ice-front is about normal to the 

 margin, so that in this case the general trend of the ice-border 

 was presumably northeast and southwest, and remained so during 

 its retreat across the county. 



The southeastern part of the county is occupied by the high 

 plateau already referred to. While the ice-front was retreating 

 across this area, the Westfield and Farmington rivers drained the 

 waters freely away from the ice-front. But when the retreat 

 had reached the western edge of the plateau, the ice-sheet 

 obstructed the drainage of several relatively small valleys and 

 caused the formation of temporary lakes. When it rested in the 

 Housatonic valley, the ice-front had free drainage to the south 

 in every position but one. From the bend south of East Lee to 

 that west of Glendale the river flows west. During one of its 

 halts the ice obstructed the passage at Glendale, so that the valley 

 to the east was occupied by a lake of considerable size. West 

 of the Taconic range in Canaan and New Lebanon in New York, 

 more lakes were produced at a later stage in the westwardly drain- 

 ing valleys of that region. 



But the largest lake in the Berkshires was that which was 

 held in the Hoosic valley. The Hoosic river flows north as far 

 as North Adams, and thence west and northwest. Throughout 

 its whole course in Massachusetts and Vermont, and for some 

 distance in New York, the retreating ice-sheet obstructed the 

 normal direction of flow. The consequence was that this 

 valley with its principal branches — the valleys of Green river 

 and the Little Hoosic — was filled first with independent lakes, 

 which later merged into one long, irregularly shaped body that 



