VOLUME XXVIII NUMBER 2 



THE 



JOURNAL OF GEOLOGY 



FEBRUARY-MARCH 1920 



THE ORIGIN OF GUMBOTIL 



GEORGE F. KAY AND J. NEWTON PEARCE 

 University of Iowa 



The name gumbotiP was proposed recently for clays of dis- 

 tinctive characters which lie on glacial till and which are related 

 closely to till. As originally defined, gumbotil is ''a gray to dark 

 colored, thoroughly leached, non-laminated, deoxidized clay, 

 very sticky and breaking with starchlike fracture when wet, very 

 hard and tenacious when dry, and which is chiefly the result of 

 weathering of drift. The name is intended to suggest the nature 

 of the material and its origin." In Iowa there is gumbotil on 

 the Nebraskan, Kansan, and Illinoian drifts. It has not been 

 developed on the lowan drift nor on the Wisconsin drift. 



SOME OF THE FORMER VIEWS REGARDING THE ORIGIN OF SUPER- 

 DRIFT CLAYS 



Until recently these superdrift clays which are now called 

 gumbotils had been found only on the Kansan and Illinoian drifts, 

 in connection with which drifts the clays had been described under 

 the name gumbo by several geologists. 



Regarding the origin of this gumbo there have been various 

 interpretations, some of which will be outHned briefly. 



'George F. Kay, "Gumbotil, a New Term in Pleistocene Geology," Science, 

 New Series, Vol. XLIV, November 3, 1916. 



