Glacial Geology in America. — Fair child. 155 
all the investigators in American glaciology,and apology is 
here offered for many omissions and possible errors.* 
THE GLACJAL THEORY. 
Announconctit. — The "drift" of the northern United 
States and Canada was not neglected by the self-taught geol- 
ogists of the early part of this century. Frequent references 
occur in the writings of those years to the strise and polished 
rocks, the stony clay, the deposits of sand and gravel and par- 
ticularly to the conspicuous erratics and perched boulders. 
These phenomena were commonly attributed to the agency of 
violent floods, and were called "diluvial." They were, however, 
so unlike any products of observable aqueous action that the 
conditions of their formation were a subject of imagination 
rather than of scientific inquiry. But this conception of water 
as the chief or only agent concerned in the production of the 
drift and striae gained such general assent and so bound the 
minds of the older American geologists that the glacial theory 
was not given at first even a respectful hearing, and it was not 
accepted until long after a majority of foreign geologists had 
adopted it for western Europe and the British Islands. — not 
indeed, until a new generation of workers had possession of 
the field. The story of the introduction, discussion and final 
acceptance of the glacial theory in America is an entertaining 
and instructive chapter in the history of science. 
The reports of the early state geological surveys, the tran- 
sactions of learned societies and the volumes of Silliman's Jour- 
nal down to about 1850 contain frequent references to "diluvial 
drift," "diluvial scratches," "tremendous currents of water," 
and terms of similar import. The first suggestion of ice as 
a contributory agent in the genesis of the drift, in the form of 
icebergs or icefloes, was made by Peter Dobson of Connecti- 
cut, in a letter to Silliman,f dated November 21, 1825. Mur- 
*The writer hopes to insert in the record of Section E for the 
next meeting (1899) a notice of anj* important additions or correc- 
tions which are brought to his attention. 
tit is not desirable to encumber these pages with a great number of 
bibliographic references. These can be found in chronologic order 
under authors' names in United States Geological Survey Bulletin No. 
127 — "Catalogue and Inde.x of Contributions to North American Geol- 
ogy, 1732-1891," by N. H. Darton. (See "Glaciology." page 417 and 
"Pleistocene," page 756.) Bulletins Nos. 130 and 135 contain the 
bibliography from 1891 to the close of 1895. 
