328 FRA NK B URSLEY TA YL OR 



southern end of the Green mountain range. In these ranges 

 heights of 2,400 to 2,600 feet are quite common. 



GENERAL ICE MOVEMENTS. 



From their studies of striae and bowlder transportation the 

 earlier geologists, E. Hitchcock,^ L. Agassiz,^ and others, found 

 that the ice-sheet moved across Berkshire county in a south- 

 easterly direction, along the Hudson river in a southerly direction, 

 and on the slope west of the river in a southwesterly direction, 

 shov/ing thus a wide southward spreading of the ice from the 

 axis of the Hudson valley. This spreading of striae charac- 

 terizes the valley through its whole length from south to north. 

 Such an arrangement of striae shows that the valley was occupied 

 at all stages of retreat by a great glacier lobe which projected 

 far south from the general line of the ice-front and spread away 

 laterally over the country both to the east and west of the river. 

 Berkshire county was therefore overrun by ice from the Hudson 

 valley lobe and may be said to lie within the territory of its 

 retreating eastern limb. The recent studies fully confirm this 

 conclusion from other evidences also, such as the alinement of 

 drumlin axes, the position of stoss-side smoothing of the hills, 

 and still more and with independent conclusiveness from reces- 

 sional moraines and border drainage. It is found that in retreat- 

 ing from southeast to northwest diagonally across the county 

 the ice-front halted fourteen times; that is to say, the east limb 

 of the Hudson lobe oscillated or wavered that many times in 

 retreating about fifty miles. 



'E. Hitchcock, "On a Singular Case of the Dispersion of Blocks of Stone at the 

 Drift Period in Berkshire County, Massachusetts," ^w. /<??<?'. .S^'., Vol. XLVII (1844); 

 and Vol. XLIX (1845); also, "Illustrations of Surface Geology," Smithsonian Contrib., 

 Vol. IX (1857, and second edition, Amherst, i860.) C. H. Hitchcock, "On the 

 Marks of Ancient Glaciers on the Green Mountain Range in Massachusetts and 

 Vermont," A. A. A. S., Froc, Vol. XIII (i860), pp. 329-35. 



'L. Agassiz, "Glacial Scratches in Berkshire and Wachusett Ranges, Massachu- 

 setts," and " Observations on a Set of Bowlders in Berkshire County, Massachusetts," 

 Boston Soc. N^at. Hist. Proc. Vol. XIV (1872). Other early papers on the 

 Richmond bowlder trains are by H. D. and W. B. Rogers, Boston Soc. Nat. Hist., 

 Vol. V (1847), pp. 310-30, and by E. Desor, ibid.. Vol. II (1848). But the most ex- 

 haustive paper is by E. R. Benton, Harvard Mus. Conip. Zool. Bull., Vol. V (1878). 



