THE ORIGIN OF GUMBOTIL 93 



The Loveland of Shimek. — ^Professor B. Shimek proposed the 

 name Loveland formation^ for gumbo-like deposits related to 

 Kansan drift in Harrison, Monona, and adjacent counties in 

 southwestern Iowa. Detailed descriptions of the formation are 

 given in his report on the geology of Harrison and Monona counties.^ 

 Here he refers to the fact that Mr. Udden described similar material 

 in Pottawattamie County as gumbo or red clay. It should be 

 pointed out that the Loveland of Shimek differs in some important 

 respects from the Kansan gumbotil of southern Iowa. The gumbo- 

 til is found only on glacial till and has a definite topographic 

 position. According to Professor Shimek the Loveland in places 

 lies not on till but on gravels. Moreover, it is not confined to a 

 particular stratigraphic plain; the term has been applied to 

 material in the lower part of the bluffs along the Missouri River 

 in some places as well as to material 180 feet higher than the bases 

 of the bluffs. Shimek considers the Loveland formation to be a 

 water deposit which was formed during the stage of melting of 

 the Kansan ice, and which has the same relation in general to the 

 Kansan drift as have the Buchanan gravels to Kansan drift. 

 This interpretation may, however, be somewhat open to question, 

 as recent studies indicate. 



The super-Kansan gumbo of Alden and Leighton. — In a recent 

 publication by Dr. W. C. Alden and Dr. M. M. Leighton there is a 

 discussion of super-Kansan gumbo in Iowa. The authors do 

 not commit themselves definitely with regard to its origin, but 

 they present evidence which they consider favorable to the view 

 advanced by Kay that the gumbo is the residuum of thorough 

 weathering and long leaching of the upper part of the Kansan till.^ 



Sufficient evidence has been submitted to show clearly that the 

 students of superdrift clays — the gumbotils and related materials — 

 have been far from agreement regarding their origin. Some 

 geologists have considered these clays to be mainly of fluvioglacial 

 origin, others beheve that they are aqueous, and still others have 



' B. Shimek, "Aftonian Sands and Gravels in Western Iowa," Bull., Geol. Soc. 

 Amer., Vol. XX (1910), p. 405. 



^ B. Shimek, "Geology of Harrison and Monona Counties," lou^a Geol. Siirv., 

 Vol. XX (1909), pp. 371-75- 



3 W. C. Alden and M. M. Leighton, "The lowan Drift," loiva Geol. Surv., 

 Vol. XXVI (1915), p. 91. 



