RECESSIONAL ICE BORDERS IN BERKSHIRE, MASS. 327 



mountains are relatively small and low. The extremes of relief 

 range from about 565 feet above sea level on the Hoosic river 

 north of Williamstown, and about 650 feet on the Housatonic 

 river below Ashley Falls, to 3,505 feet on Greylock mountain and 

 2,624 feet on Mount Everett, otherwise known as the Dome of 

 Mount Washington. The two principal rivers are the Housa- 

 tonic, flowing south, and the Hoosic, flowing north and northwest. 

 Their valleys are the principal valleys of the county and are 

 united as one trough across a col about three miles northeast of 

 Pittsfield. The altitude of this col is about 1,120 feet above 

 tide. Some of the main sources of the Hoosic are near the col, 

 but the Housatonic, coming from the east, receives branches of 

 some size from the north and west near Pittsfield. The exten- 

 sive area of Stockbridge limestone stretching south from the 

 vicinity of Pontoosuc lake three miles north of Pittsfield gives 

 rise to the broadest valley of the county. Its usual breadth is 

 from four to six or seven miles, but for twenty miles south- 

 southwest of Pittsfield it is broken by isolated faulted mountains, 

 and between these from Glendale to Housatonic the river flows 

 through a narrow gorge-like valley. 



Mount Washington, which is the highest point of the southern 

 Berkshires, rises in considerable part above 2,000 feet. Except- 

 ing this, the higher lands in the southern and southeastern 

 Berkshires commonly reach an altitude but little above 1, 600 to 

 1,800 feet. The plateau of the southeastern part, however, is 

 trenched by the deep, narrow valleys of the Westfield and Farming- 

 ton rivers and their branches. 



In the northern third of the county the reliefs become greater. 

 Excepting in the vicinity of Williamstown, the Hoosic valley is 

 seldom more than a mile wide in its lower levels. South of 

 Williamstown a considerable area of limestone develops a broader 

 lowland along Green river, and where this merges with the 

 Hoosic valley it has the effect of broadening the latter. 



The mountain masses bounding the Hoosic valley are con- 

 siderably higher than those to the south. A large part of the 

 Greylock mass rises above 2,000 feet, as does also the main crest 

 of Hoosac mountain. East mountain, the Taconic range, and the 



