THE GLACIAL PERIOD^ 295 
■or qualities which through'correlations yield signs of natural laws, and the floral 
•organs as indicativcjof the motive of the wild plant's life furnishes the key. If these 
views are correctly stated, then it is seen that an agricultural botany as an annex to 
the natural botany is imperatively required for the purpose of furthering classifica- 
tion and identification of domesticated plants, and such an annex must vary in its 
methods as widely from the methods of the natural botany as cultivated plants 
vary from feral plants, the]key to the motive being in one case the use, while in 
the other the floral organs. 
GEOLOGY AND PALEONTOLOGY. 
THE GLACIAL PERIOD. 
PROF. I. C. WHITE. 
Read before Section E, August ijth, 
[The Geological Section is universally conceded to be the one in which the 
■newest and most interesting scientific facts have been brought out. A matter of 
special interest which it has discussed has been the theories of the glacial period 
•of North America. It may be interesting to briefly review the history of these 
theories. It was noticed three or four decades ago by the eminent naturalist, 
Agassiz, that through the United States north of the Ohio River, there were scat- 
tered formations of gravels, boulders, sandstones and clays, which were in geo- 
logical positions and relations similar to those at the foot of European glaciers. 
These deposits were utterly dissimilar from any of the prevailing formations of 
the surrounding country. The question then was, whence came these strange 
visitors? It was found that to the north of these deposits were large formations 
of the same kind of material, which seemed to indicate that some mighty force 
had torn these boulders, etc., from their original beds and carried them south, 
•sometimes a mile, sometimes looo miles. The hypothesis was then suggested that 
this was the work of a number of geologists who had made desultory surveys of 
these formations, but no scientific survey of them had been made up to seven or 
•eight years ago, when Prof. Chamberlin, then of Beloit College, and Prof. Cook, 
of New Jersey, set out to make a thorough study of this glacial hypothesis. Prof. 
Chamberlin went to Europe to examine the beds of glaciers there in order to 
thoroughly prepare himself for original investigation. The study of these forma- 
tions was exceedingly careful and painstaking, extending from Cape Cod and 
Long Island to the Sierra Nevada Mountains. Up to this time, two theories had 
each their advocates — that these formations were dropped from glaciers moving 
south, and that they were deposited by icebergs. The work of these two explor- 
ers, however, brought forth such an array of facts as to positively show that this. 
was the work of ice, and that the glacier theory was the only tenable one. 
