Address before the Association of American Geologists. 249 



in regard to every particular theory that has been proposed. I con- 

 fess myself to have been long of that number. Yet it has seemed 

 to me of useful tendency to make isolated inferences from the 

 facts developed ; and although they may seem to favor rival hy- 

 potheses, and will need modification, as new light falls on the 

 subject, yet they will form the elements out of which a legitimate 

 theory will ultimately spring. Allow me to present for your con- 

 sideration, a summary of the most important of these inferences, 

 as they have been developed to my own mind in examining the 

 diluvial phenomena of this country. 



In the first place, these phenomena must have been the result 

 of some very general force, or forces, operating in the same gen- 

 eral direction ; that is, southerly or southeasterly. For in a 

 southerly direction has the drift been so uniformly carried, and 

 the furrows and scratches on the rocks so generally point south- 

 erly, that the force which produced these effects must have tend- 

 ed thither. Our valleys have, indeed, considerably modified the 

 course of the drift ; but not enough to contradict the general 

 statement. It would be strange if careful examination should 

 not discover here, as in the Alps and in Great Britain, that the 

 moving force had sometimes been exerted outwardly from the 

 axes of high mountains. But I am not aware that as yet any 

 facts of importance in favor of such an opinion, have been brought 

 to light. At any rate, the evidence of a force urging detritus 

 and bowlders in a southerly, or more strictly in a southeasterly 

 direction, is too marked, and has been noticed by too many inde- 

 pendent observers, over a breadth of nearly two thousand miles, 

 to be doubted ; even though local exceptions should be discover- 

 ed ; — and such a uniformity of direction over so vast an area, in- 

 dicates a very general agency. 



Secondly, this agency has operated at all altitudes, from the 

 present sea level, and probably beneath it, to the height of three 

 thousand or four thousand feet. In New England, most of our 

 hills and mountains, not excepting insulated peaks, not higher 

 than three thousand feet, are distinctly smoothed and furrowed 

 on their tops and northern slopes, and upon their east and west 

 flanks, to the bottom ,c)f^ the lowest valleys. Dr. Jackson sup- 

 poses he has found ^tfensported 'detritus on Mount Katahdin, 

 four thousand feet higWlV*' out he co.uld discover, no marks of this 

 action at the summitiofel^e White mountains of New Hampshire, 



Vol. xLi, No. 2.— July-Scpt.'l841.. 32 



if v 



Ay V 



