Address before the Association of American Geologists. 255 



ice melted away.* The lateral moraines are perhaps most com- 

 mon, especially if, with Dr. Buckland, we regard our terraced val- 

 leys as modifications of these ; but I am confident that in our 

 mountain valleys, the terminal and the medial moraine are not 

 infrequent. I have long been convinced that the agency of ice 

 was essential to explain these accumulations ; but I was not aware 

 that their antitypes existed in the moraines of the Alps. 



In the second place, this theory explains in a most satisfactory 

 manner, the smoothing, polishing and furrowing of the rocks at 

 different altitudes. All these effects are perfectly produced be- 

 neath the glaciers in the Alps ; nor can I conceive of any other 

 agent by which the work could be executed. It certainly was 

 not done by currents of water alone. One has only to cast his 

 eye upon the splendid plates by Agassiz, of the polish and striae 

 produced by the glaciers, to be satisfied that the multitudes of 

 examples of analogous phenomena in New England, and in New 

 York and Ohio, as described by Profs. Dewey, Emmons, and 

 Locke, and Dr. Hayes, are precisely identical with those in the 

 Alps. 



In the third place, it explains the transportation of bowlders, 

 and their lodgment upon the crests and narrow summits of moun- 

 tains, and that often without having their angles rounded. 



In the fourth place, it accounts for the occurrence of deposits 

 of clay and sand above the drift. For it furnishes the requisite 

 quantity of water to fill the valleys, and the means of damming 

 up their outlets for a season. 



In the fifth place, it shows us why these deposits of clay and 

 sand are almost completely destitute of organic remains, either of 

 animals or plants, although probably centuries must have been 

 consumed in their formation. 



In the sixth place, it accounts for some rare and peculiar phe- 

 nomena connected with diluvial action, which seem to me inex- 

 plicable on any other known principle. I shall name only two. 

 The first is, that the northern slopes of some of the mountains 

 of New England, although quite steep, and their summits 

 rounded, exhibit strise and furrows which commence several 



* Descriptions of some of these with sketches, will be found in my Report on 

 the Geology of Massachusetts, publislied in 1833: but more numerous descriptions 

 and drawings are given in the Final Report just publislied. See especially Figs. 

 15, 19, 73 and 74, of the wood cuts, and plate 3 of the lithographs. 



