1890 .] 
459 
[Leverett. 
taming pebbles, sand and clay. The change from noncalcareous 
subsoil to the calcareous till is usually gradual, seldom, if ever, so 
abrupt as should be expected on the theory of the superglacial ori- 
gin of the one and the subglacial origin of the other, — not so ab- 
rupt as is usually the change from the oxidized to the unoxidized 
till. If we accept, with some, the theory that the oxidized till is 
all superglacial, the extent and character of the leaching have still 
the same significance in denoting a lapse of time as on the theory 
of its subglacial origin. 
The forest bed occurs at several other horizons than the one in- 
dicated above. It is found to a limited extent between the sheets 
of newer drift, but here it has a calcareous till immediately below 
it, and this till is not perceptibly older than that above the soil, 
there being little or no oxidation. Similarly, in the older drift there 
are frequently exposed thin carbonaceous beds between the oxidized 
and unoxidized tills of which it is composed, and also interstrati- 
fied with the unoxidized tills, but accompanied by little or no leached 
subsoil. Such soils may have been formed and buried during periods 
of oscillatory retreat of short duration and of limited extent. 
In brief, the evidence from this district, so far as its buried soils 
and leached tills have a bearing, seems to teach that there were two 
main epochs of glaciation, each characterized by oscillatory retreats, 
between w T hich was an epoch of deglaciation of considerable length. 
Dr. J. Playfair McMurrich, Messrs. C. P. Bumpus, J. E. Clarke, 
H. L. Rich, Harris Kennedy, H. S. Hunnewell, Marshall H. Sav- 
ille, Charles P. Bowditch, Nathaniel Allen and Miss Julia B. Platt 
were elected Associate Members. 
General Meeting, January 15, 1890. 
The President, Prof. F. W. Putnam, in the chair. 
The meeting was called to continue the discussion of the “ Cli- 
matic Condition of the Glacial Period ” begun at the last meeting. 
The following remarks were made on this subject : 
