RECESSIONAL ICE BORDERS IN BERKSHIRE, MASS. 363 



by the ice-border at its successive recessional halts were distinct 

 individuals without overlappings ; that by the faintness of the 

 moraines and other border phenomena, the halts may be judged 

 to have been of relatively short duration, although when we con- 

 sider the number of halts which occurred within the interval of 

 fifty miles it can hardly be said that the retreat of the ice-front 

 was rapid, or that it was a sudden dissolution with great floods, 

 as pictured by Dana^ and others. 



That this ice was Hudson ice and came over the Berkshires 

 from the central axis of the Hudson valley seems to be indicated 

 further by the fact that within the area of the two quadrangles 

 studied no stones or bowlders were found which might be sus- 

 pected of coming from Canada or from the Adirondacks. It 

 seems that the Adirondack ice never crossed to the east side of 

 the Hudson-Champlain trough, and further that any bowlders 

 which may have started from Canada down the axis of this 

 trough found it impossible to keep the line of that axis far 

 enough to reach the Berkshires. The continual divergence of 

 the ice to one side or the other of the axis appears to have side- 

 tracked all the Canadians before they got so far south. The 

 same fact seems to account in part for the very local derivation 

 of nearly all the drift in the Berkshires. Exceedingly little 

 came from points as far north as Whitehall, N. Y. The great 

 spreading ice-stream which moved down the Champlain-Hudson 

 trough domineered those valleys through every stage of the 

 glacial invasion and was never diverted from its course. 



In his recent admirable report on the glacial geology of New 

 Jersey, Salisbury observes that "the edge of the ice might have 

 halted in one place and not at another at the same time. 

 Moraines of recession are therefore sometimes not traceable for 

 long distances." ^ 



'J. D. Dana, "The Flood of the Connecticut River Valley from the Melting of 

 the Quaternary Glacier," Atn. Jour. Sci., Ill, Vol. XXIII (1882), pp. 87-97, 179-202, 

 360-73; Vol. XXIV, pp. 98-104. C. H. Hitchcock, "The Glacial Floods of the 

 Connecticut River Valley," A. A. A. S., Proc, Vol. XIII (1883). Warren Upham, 

 "A Review of the Quaternary Era, with Special Reference to the Deposits of Flooded 

 Rivers," Am. Jour. Sci., Ill, Vol. XLI (1891). 



^"Glacial Geology," Geology of New Jersey, Vol. V, p. 89. 



