196 THE PHENOMENA OF DHIFT, OK 



There is one very curious variety of the moraines that have 

 been described, which I have not noticed above, because I suspect 

 they have been modified since their formation, by alluvial agency. 

 They are merely insulated conical tumuli of gi-avel, sand, and 

 bowlders, usually occurring at the foot of mountains. Hence it 

 is probable that they are the remains of detritus, which has been 

 more or less worn away by streams descending from the hills. I 

 do not feel fully satisfied with this theory ; first, because it is 

 diflicult to conceive how such perfect tumuli should be thus pro- 

 duced, some of them nearly one hundred feet high : secondly, 

 because some of them occur at a distance from any mountain. 

 Still, I cannot conceive how they should be produced in any other 

 way ; unless possibly by being conveyed upon the tops of ice- 

 bergs, which melting, left them of a conical shape. So artificial 

 is their appearance often, that they have in various countries been 

 regarded as artificial. Professor Struder lately described §ome 

 of these in Berne, in Switzerland, which " were there universally 

 supposed to be the works of art:" but on excavating them, they 

 were found to consist of Alpine bowlders and gravel. Probably 

 many of the mounds in our western States, now regarded as the 

 works of man, will be found to have had a similar origin ; or to 

 be the remains of alluvial deposits, worn into various shapes by 

 water, upon which man has erected fortifications and other 

 structures.* 



The deep valleys of Berkshire county, in Massachusetts, pre- 



* I have several times advanced this opinion in my publications upon geology ; and as 

 I expected, it has met with strong opposition and ridicule from ^^Tite^s of almost every 

 grade. But the more I learn concerning these mounds, and concerning similar tumuli on 

 the eastern contment, the more conxinced am I, that many of them, I mean the larger 

 ones, are more indebted to nature than to art. I wish to be distinctly understood as 

 admitting the existence of artificial mounds and ridsres in our western States, as well as 

 in the eastern world. But I maintiiin, that in many cases, man, instead of piling up with 

 vast labor these mo\uid.s and ridges, has chosen those already prepared for him by nature, 

 as convenient spots on which to erect fortifications and other structures. If these larger 

 mounds shall be cut throusrh. and the materials be found not sorted or stratified, but 

 evidently of artificial origin, ridicule will be found a much more powerful weapon ■with 

 which to combat my opinion, than it now is. JVoits verrons. 



In support of my views I would refer to Professor V.\nuxem's Report on the Geology 

 of New York, p. 217, and to Rev. S. Parker's Exploring Tour beyond the Rocky Moun- 

 tains, third edition, p. 39. 



