ESKERS ASSOCIATED WITH THE PLATEAUS. 191 



900 feet, 880 feet, and 875 feet. The most western, which is crossed by 

 the southeast part of Pennsylvania avenue, was perhaps originally united 

 with the next, from which it is divided by a creek and railroads in a gap 

 nearly 100 feet deep. The most northeastern of these plateaus is crossed 

 by Whitall street between De Soto and Edgerton streets. 



Farther northeastward, between the last of these plateaus and lake 

 Phalen, the moraine belt rises to about 900 and 920 feet, respectively, at 

 the Cleveland and Harrison schools, where, as in all that eastern part of 

 the city, little or no modified drift overlies the knolly and hilly till. 



ESKERS ASSOCIATED WITH THE PLATEAUS. 



No eskers were found, though they were carefully looked for, in the 

 line of continuation from the plateaus last described, which, with the 

 Summit avenue plateau, constitute a series four and a half miles long 

 from west-southwest to east-northeast. Excepting the eskers, already 

 noted, connected with the east side of the Hamline plateau and with the 

 west end of the sixth plateau, the only other gravel and sand ridge noted 

 in or near the area of Saint Paul, such as can be referred to the class of 

 eskers, is the prominent ridge extending a mile east-northeastward from 

 the northeast part of the Corao plateau. It seems to have been formed 

 in the ice walled channel of one of the chief streams which at the same 

 time were depositing the Como plateau in a wider yet still ice-enclosed 

 embayment melted out of the margin of the ice-sheet. 



In its length of a mile this esker ridge, lying just outside the city 

 boundary, rises gradually from about 950 feet to 1,010 feet, culminating, 

 at its northeastern end, in the hill on whose top the reservoir of the Saint 

 Paul water works is built, having its high-water line 1,003 feet and its 

 surrounding grassed parapet 1,007 feet above the sea. The material of 

 this ridge is almost entirely sand and gravel, with water-worn cobbles 

 up to six or eight inches in diameter, and bearing on the surface very 

 rare angular boulders one to two feet (and in one instance even four feet) 

 in diameter. Steep slopes fall off about 75 feet to the north, east, and 

 south. 



At a distance of a third of a mile southward the esker gravel and sand 

 merge into a similar deposit, which is spread as a flat plain, with its 

 surface at 915 to 925 feet, extending a half mile from east to west, with 

 a slight southward descent. A hollow about 40 feet deep divides this 

 plain from the somewhat higher fourth plateau, which is close southeast. 



Glacial Drift and Moraine Belts. 



Professor N. H. Winchell and the present writer, in the Minnesota geo- 

 logical reports and in earlier papers, have discriminated the red till brought 



XXVIII— Bull. Geol. Soc. Am.. Vol. 8, 1896 



