1892-1 23 fRarton. 
the (^losiiijj; stages of the last ice invasion had a milder »',liiuat,e tlian 
the present, and that Lake Agassiz was therefore seldom frozen 
o\ er, I may simply say that other experts do not think so. If all 
experts are agreed, their opinion may be quoted at least to show 
tlie fashion of thought at the time, if not to demonstrate a certain 
loiiclusion ; hut when experts differ greatly in their opinions, it is 
llieii- reasons and not their opinions that should serve as the 
t'oundation for further theorizing. This is the more important as 
a principle of work, because it is so often the case that a carefully 
guarrled ophiion or a cautiously qualified suggestion in the original 
statement becomes a definite opinion in the first quotation, a con- 
clusion in the next cjuotation, ami an establishe<l fact in its pop - 
nlai- rendering. 
It may seem from these remarks, Mr. President, that I am tak- 
ing oidy an antagonistic attitude towards Mr. Upham. Such is 
not my feeling. We are still, as we have been for a number of 
years, working together towards a common goal, along with 
others who are striving in the same direction. Our work is not 
mechanical, according to a set pattern, and it must therefore be 
Hav(»re(l by our individual opinions on the many questions that 
are always involved in so complicated a problem as this. We 
agree about as closely as field geologists may on many questions ; 
but we seem to differ rather seriously at present regarding the 
manner of interpretation and the stage reached by the investiga- 
tion of drumlins. 
Mr. G. II. Barton said : I have been engaged during the last 
three seasons in studying the drumlins of Massachusetts and 
mapping nearly their entire distribution over the State, and I am 
naturally much interested in any and all theories that have been or 
may be advanced respecting their origin. Especially welcome is 
a new theory as none of the older seems sufficient to account for 
all the phenomena presented. Indeed it is probable, as suggested 
by Professor Davis, that the accumulation of these hills may be 
due to different causes and that no one general theory will 
account for their origin in all cases. 
Various areas give different types as seen most readily in com- 
paring the more rounded and slightly lenticidar hills in some 
parts of Massachusetts with the extremely elongated hills of cen- 
tral New York. In one area they are found scattered over the 
