126 PLEISTOCENE OF INDIANA AND MICHIGAN. 



MARSEILLES MORAINIC SYSTEM. 

 COURSE AND CORRELATION. 



In Monograph XXXVIII the Marseilles rnorainic system of the Illinois lobe was traced 

 as far east as the village of St. Anne, 111., a few miles southeast of Kankakee, and it was noted 

 that its natural continuation lay eastward along a ridged belt and bowldery strip north of 

 Iroquois River in Newton and Jasper counties, Ind., to which the name "Iroquois" moraine 

 was applied. It was suggested that this "Iroquois" moraine is the result of two ice advances 

 differing widely in date as well as in direction, one advance being from the north in the earlier 

 Wisconsin substage, and the other from the south or southeast in the later Wisconsin substage. 

 Much of the relief along the moraine was ascribed to the earlier advance, and only the bowlders 

 and the low knolls on its surface were considered to be the product of the later one. As an 

 alternative it was suggested that the moraine might stand hi the line of an interlobate spur 

 formed at the junction of the Illinois and Erie-Saginaw lobes, and that the numerous bowlders 

 are a result of this interlobate condition. The date of the formation of this interlobate spur was 

 placed in the later Wisconsin substage. 



It now seems necessary to suggest another interpretation, namely, that the "Iroquois" 

 moraine is simply the continuation of the Marseilles rnorainic system and was produced entirely 

 by the Illinois lobe. This is the simplest interpretation of the three and seems to be the best 

 supported, for the others lack the evidence necessary fully to establish the complex history 

 postulated for them. If the "Iroquois" rnorainic tract be examined in cross section it is found 

 to resemble the Marseilles in amount of relief, in breadth, and in having a long gradual slope on 

 its north or iceward side, and a rather abrupt descent on its south or landward side. The rise 

 from the plain to the crest of the moraine on the north amounts to 20 to 40 feet hi about 2 

 miles and on the south to 30 to 50 feet in less than 1 mile. These similarities and the further 

 fact that the "Iroquois" moraine lies in the line of natural continuation of the Marseilles system 

 strongly favor the thud view. 



The width of the " Iroquois " moraine is generally between 2 and 4 miles, but bowldery areas 

 on its north border extend about 2 miles farther north to the southern edge of an extensive 

 sandy plain traversed by Kankakee River. 



The southern border of the "Iroquois" moraine lies 1 to 4 miles north of Iroquois River in 

 Newton and Jasper counties, Ind., and trends south of west and north of. east. In eastern 

 Jasper County it turns northward and extends nearly to the northeast corner of the county. 

 It dies out as a definite ridge 4 or 5 miles south of Kankakee River, and its continuation to the 

 east is uncertain. 



Inasmuch as this moraine dies out at the northeast in a sandy plain, some uncertainty is 

 felt as to its continuation farther east. One possible correlative is a moraine which begins near 

 Bass Lake, in Starke County, about 18 miles to the east. Between the two lies a tract which, 

 though generally sand covered, bears a broad low ridge from the north end of the "Iroquois" 

 moraine at San Pierre to North Judson and carries patches of bowlder-strewn till from North 

 Judson to Bass Lake, thus nearly filling in the interval between the ends of the well-defined 

 moraines and giving some strength to the correlation. The correlative moraine, which leads 

 southeastward front Bass Lake, appears to have been formed by the Saginaw lobe, for it lies 

 on the immediate outer border of the great Maxinkuckee moraine of that lobe, discussed below. 



TOPOGRAPHY. 



The highest points noted on the Marseilles system in the district north of Iroquois River 

 are north of Rensselaer, where an altitude of 765 to 775 feet above sea level is attained. Much 

 of the moraine reaches between 700 and 725 feet. 



The surface of the ridge carries low knolls and ridges, among which sloughs and shallow 

 basins are inclosed. Part of the bowlder-strewn plain north of the ridge is also occupied by low 

 swells and hummocks, among which are shallow basins, but much of it is flat. 



