Man and the (rlaeial Period. 189 
introduced into it by dropping from above, or b}- any other 
means. Upon my examination of these deposits in 1891 I ex- 
pressed the following opinion, which, in the light of further reflec- 
tion and wider acquaintance, has become a strong conviction: 
"When a question so important as that of the date of the ap- 
pearance of man may depend upon the correct determination of 
the original position of a stone in such loose and poorly assorted 
gravel it is well to withhold judgment until every line of evi- 
dence has been thoroughly worked out. As the evidence now 
stands it is, in my opinion, not conclusively proven that man in- 
habited this portion of the Ohio valle}' during the glacial period." 
M.VX ANI> THE CtLACIAI. PeRIOD. 
Waiiuen Upiiam, Somerville, Mass. 
The extraordinary interest aroused b}^ Prof. Wrighfs new book, 
"Man and the Glacial Period," seems to me attributable to the 
present transitional state of glacial geology, which, both in Amer- 
ica and in Europe, especially in the United States and England, 
is passing from old to new interpretations of the great body of 
observations faithfully noted during manj^ years. Whether the 
workers have seen the significance of their observations dimly and 
erringly or with clearness and sound judgment, in either case we 
owe much to their (Efforts as pioneers. If any investigators now 
.see farther or better than their fellow- workers or than those of 
other countries or former years, it is largely due to the vantage 
ground given by the previous literature of the Ice age. There- 
fore every amateur worker who comes into this field and devotes 
his spare time to glacial explorations and studies, as Prof. Wright 
has done during the past fifteen years of our acquaintance, de- 
serves the hearty welcome of all fellow-glacialists. 
Prof. Wright is adversely criticised chiefly for his beliefs, first, 
in the unity or continuousness of the Ice age on this continent, 
and, second, in the contemporaneous existence of men occupying 
the entire width of the United States along the southern bound- 
ary of the ice-sheet. Opposed to the first of these opinions is 
the belief of his critics, that the glacial period here comprised 
two distinct epochs of glaciation, divided b}' a long intex'glaeial 
epoch. It is claimed that the evidence for two glacial epochs is 
