102 PROCEEDINGS OF THE AMHERST MEETING 



Discussed by W. M. Davis and J. B. Woodworth, with reply by the 

 author. 



Discussion 



Professor Woodworth called attention to Edward Hitchcock's recognition of 

 glacial action and moraines in the Cape Cod region, published in an intro- 

 ductory (postscript) to his final report of 1841, evidently following in Agassiz's 

 Essai of 1841. 



WHAT CONSTITUTES THE ALTAMONT MORAINE? 

 BY FRANK LEVERETT x 



(Abstract) 



The Altamont moraine of the western limb of the Des Moines icelobe of the 

 last, or Wisconsin, stage of glaciation was first noted by Prof. T. C. Chamber- 

 lin in 1878, and is described in his paper in the Third Annual Report of the 

 U. S. Geological Survey (pages 378, 388, 393). He supposed it to be the outer 

 moraine of the Des Moines lobe, and on the basis of this supposition the name 

 Altamont has been applied to the outer moraine, both in the Des Moines lobe 

 and in the Dakota, or James River, lobe to the west. 



In the course of field-work in eastern South Dakota in 1912 the present 

 writer found that the moraine on which the village of Altamont, South Dakota, 

 stands is not the outer moraine of the Des Moines icelobe, there being a strong 

 moraine outside which passes through Bemis, South Dakota. It was also 

 found that it is this moraine, and not the one passing through Altamont, that 

 has been mapped as the Altamont moraine in the reports of the Minnesota and 

 Iowa Geological Surveys. 



It was not until 1921 that the tracing of the moraine that passes through 

 Altamont was carried around the loop in northern Iowa, in a joint survey by 

 J. H. Lees, of the Iowa Geological Survey, and the present writer. The results 

 of this survey and that of the present writer in Minnesota and South Dakota 

 are set forth in figure 1. It is found that this morainic belt embraces the 

 moraine south of Fort Dodge, Iowa, to which Dr. C. A. White called attention, 

 under the name "Mineral Ridge," in 1870. 2 Doctor White suspected it to be a 

 moraine, and interpreted it to mark a halt of the receding ice-border. He also 

 recognized a later moraine in northern Iowa. 



The outer moraine of the Des Moines lobe splits up into four weak members 

 in northern Iowa, and these fade out into gently undulating ground moraine 

 near the southern end of the lobe, in the vicinity of Des Moines, Iowa. The 

 moraine which passes through Altamont does not show such weakness, but is 

 a strong, well defined feature around the entire circuit of the morainic loop. 

 On this account, as well as because it is the identical moraine to which Cham- 

 berlin applied the name Altamont, it seems advisable to let it carry the name 

 and discontinue its application to the outer moraine. The writer proposes to 

 apply the name Bemis to the outer moraine of the Des Moines lobe. 



The course of the Altamont moraine in the Dakota, or James River, lobe 

 has not been determined, so it can not now be stated whether it forms the 

 outer moraine or, as in the Des Moines lobe, lies well within the border. The 



1 Published by permission of the Director of the Dnited St:ites Geological Survey. 



2 Geology of Iowa. vol. i. pp. !>S-!)0. 



