60 
IOWA ACADEMY OF SCIENCES 
Kaneville, and rising a few feet above the till plain of the region. Well 
borings in the delta region have shown a deposit of gravel and sand 
30 or 40 feet deep, but most of the area is covered with humus, giv- 
ing mesophytic conditions and mxaking excellent farm-land, with here 
and there a surface exposure of gravel, bringing xerophytic conditions 
and easily available gravel and sand, the largest of these being on the 
Spenser farm, about a mile from Kaneville. 
* Bald Mound and Johnson’s Mound are but two high elevations of 
the undulating till sheet left by the glacier (Wisconsin till sheet) and 
extending at least from Plano, in Kendall county, northward through 
Sugar Grove and Blackberry townships in Kane county. The esker 
crosses this area of till knolls in Sugar Grove township, and the gen- 
eral topography of the till area is not greatly different from that of 
the more tumultuous portion of the esker, so that the casual observer 
would find it difficult to distinguish between this portion of the esker 
and the general till-topography. 
The esker and the till knolls are quite similar as to nature of deposit, 
all containing gravel, with beds of sand and clay interspersed, and all 
form the -main deposit, running and percolating water carrying the 
finer portions down to a lov/er level. As the writer traveled over por- 
tions of this area last summer, he was impressed with the former 
possibility of an excellent ecologic study, but pasturing, defores- 
tation, and cultivation have now gone on to such an extent as to leave 
only a few spots in their original condition, while the gravel is of 
great value for commercial purposes, and the esker was being removed 
rapidly while we were studying its flora. The accompanying map shows 
the position of the esker, the esker valley and the distribution of tbt. 
till knolls in the surrounding region. To explain further the origin of 
the till and the esker is too far removed from the present purpose, 
but those interested are referred to a paper by Frank Leverett, “The 
Illinois Glacial Lobe”, in Monograph 38 of the United States Geological 
Survey. 
Dr. H. C. Cowles, of Chicago University, was with the writer during 
the first day’s study of the flora, and aided considerably in the study 
of the spermaphytes. The elevation and the gravelly and calcareous 
nature of the knolls and the esker were found to have resulted in cer- 
tain floristic peculiarities, purely xerophytic so far as the seed plants 
are concerned, but both xerophytic and calcareous as regards the lichens. 
On the rounded hill we found various xerophytic seed-plants and lichens, 
while the conspicuous fringe of blue vervain {Yerhena stricta) extending 
half way up its slope on the north and east, the fringe showing a well- 
marked zonal arrangement and becoming very thin and appearing at 
a lower level on the south and southwest sides, the direct rays of tbe 
sun and the dry southwest winds of summer doubtless making the con- 
ditions too dry for this semi-xerophytic species (Fig. 1). The esker, 
at the point studied, back of the Dorr residence, extends nearly due 
east and west, and we found trees fringing the north slope, while the 
