SAGINAW LOBE. 125 



knolls 20 to 30 feet high are numerous. So far as can be determined by exposures in gullies 

 these knolls are composed largely of fine sandy gravel with only local beds of cobble or coarse 

 material. Bowlders are not so numerous as on the bordering plain. 



When first examined by Chamberlin and the writer in 18S6 and 1S87 this kame belt was 

 thought to have been formed on the western edge of the Erie ice lobe after the ice had with- 

 drawn from the Iroquois basin. By means of bowldery strips and scattered knolls it can be 

 connected toward the northeast with a strong moraine, also thought to be a product of the 

 Erie lobe. The failure to find any definite continuation toward the south left the interpretation 

 somewhat in doubt. The region was reexamined hj the writer and by A. H. Purdue in 1895 in 

 connection with other studies in that region and was visited again hy the writer in 1902. The 

 correlation can not be said to be fully settled yet, but it now seems probable that the kame belt 

 was formed while the ice covered the territory west as well as east of it, and it may be a correla- 

 tive of the Nebo-Gilboa ridge. This kame belt and the bowldery tracts that extend northeast 

 from it across northwestern Carroll County are thought to mark the junction of ice movement 

 from the Erie and Saginaw basins before distinct lobes appeared in the process of the melting 

 away of the ice. The evolution of the lobes is brought out step by step in the discussion of 

 later moraines. 



The continuation of the border of the Erie lobe across the Wabash seems likely to be found 

 in a strip of gently undulating land with numerous basins that leads from Delphi southeastward 

 past Flora to Wildcat Creek at Cutler, where it develops locally into a rather pronounced moraine. 

 It was formerly thought that the ice border may have taken a southward course from near 

 the mouth of the Tippecanoe along a bowldery belt on the east side of Wabash River and thus 

 made connection with the moraine and bowlder belt a few miles east of the city of Lafayette. 

 Owing to the poor development of morainic features in the district east of the Wabash, the 

 mapping and interpretations must necessarily be somewhat indefinite. 



BOWLDERY AREAS. 



Bowlder-strewn areas are common on till plains in southern Jasper and western White 

 and Pulaski counties, as well as in the vicinity of the Chalmers kame belt. They are not so 

 numerous on the till plain on the immediate border of Iroquois River. Considerable time 

 was spent in mapping these bowlder belts by Chamberlin in 18S6 and by Purdue and the writer 

 in later years, it being thought that their distribution might throw light on the manner in which 

 the ice disappeared from the region. But though belts of considerable length were found no 

 system in then - distribution was detected. They trend in various directions and are especially 

 abundant where surface sand is thin or wanting; indeed, they fade out as sandj r areas are 

 approached. Throughout much of the district bowlders are numerous where the bedrock is 

 within a few feet of the surface, but they are also present where the drift is thick. It seems 

 doubtful, therefore, if high altitude of rock surface was of much importance in determining their 

 lodgment. Their distribution was probably determined by somewhat indefinite conditions 

 within or upon the ice sheet in its vanishing stage. 



As is common in belts along moraines the bowlders differ in kind and size and degree of 

 angularity. The majority are granite, but many are of other rock types, among which are a red 

 jaspery conglomerate apparently derived from Huronian ledges north of Georgian Bay, and a 

 greenish conglomerate containing granite pebbles. Few are representatives of local rock forma- 

 tions. Many are 2 feet or less in diameter and few exceed 4 feet. They range from well rounded 

 to sharply angular, the rounding appearing to have been produced by weathering rather than 

 by water action. The absence of striated or glacially planed surfaces on all but a few of the 

 bowlders distinguishes them from rocks included in the drift, many of which show glacial planing 

 and striation. 



