258 Address before the Association of American Geologists. 
more than two hundred feet high, which occur in Plymouth and 
Barnstable counties in Massachusetts. I see nothing in this the+ 
ory that will explain such astonishing accumulations in such cir- 
cumstances ; and yet their existence may not militate against its 
truth. . For even the present mighty glaciers of the Alps, may 
give us but a faint idea of the effects of the advance and retreat 
of a sheet of ice thousands of feet thick. We have no evidence 
in this country, that any of our mountains have been elevated 
since the glacial epoch ; as seems to be proved to have been the 
case with the Alps, and this circumstance may have produced a 
considerable modification of glacial action on this continent. 
Ido not mention these difficulties (to which I might add more,) 
as any strong evidence against this theory. For so remarkably 
does it solve most of the phenomena of diluvial action, that J am 
constrained to believe its fundamental principles to be foundedin 
truth. Modifications it may require: for it would be strange 
enough if it had already attained perfection, even in the skillful 
hands that have thus far framed and fashioned it. But I ean 
hardly doubt that glacio-aqueous action* has been the controlling 
power in producing the phenomena of drift. Having hovered so 
long over the shoreless and troubled ocean of uncertainty aud 
doubt, I may be too ready to alight on what looks like terra firma. 
But should it prove a Delos, I have only to pluses see — 
again, when it sinks beneath the waves. 
I have dwelt long on this subject; its great importance, its in- 
teresting aspect at this time, and its wide developement im our 
country, must plead my apolog 
_ In referring to our alluvial Yrhlsrioeis T shall call your atten- 
tion only to a single subject, and that is, microscopic palaon 
tology. The splendid discoveries of Ehrenberg in this depart 
ment, were yet fresh among us, when Prof. Bailey demonstra- 
ted that similar relics abound in this country.. They form eX 
tensive deposits, covering many acres, and sometimes seve! 
feet thick, beneath our peat-bogs. The substance appears to be 
e Bergn amehl, or mountain. bg Sossil farina, of the Germans, 
~ is mostly composed of the Shields or Carapaces of the family 
@. Some do, ane yet doubt the animal origit of 
= rt 
co Lmean the, jriota sation of desing wi 
has ex d the +e ioe and wanes eax 
