216 ILLINOIS STATE ACADEMY OF SCIENCE 



times of high water but may become quite dry in the late 

 summer and fall. The line between these plains and the 

 surrounding uplands is always clearly marked and shows 

 evidences of shore erosion, as if it had marked the shore 

 line of a lake which filled the whole depression at some 

 time in the past. 



The uplands show a marked alkalinity, and the glacial 

 material of which they are composed contains many 

 boulders and pebbles of lime-stone. The low flat borders 

 are also alkaline, while the substratum under the bog 

 vegetation is uniformly acid. The soil of the plains con- 

 sists of black peat or muck, sometimes interbedded with 

 sandy wash from the uplands, but this deposit is very 

 shallow, not being more than six feet deep at the maxi- 

 mum. At the edge of the bog vegetation the bottom drops 

 off rapidly and the character of the peat changes to a 

 dark yellowish brown and contains fragments of bog 

 plants. This kind of peat underlies all of the bog vege- 

 tation, and is everywhere over ten feet in thickness and 

 probably much thicker in the central parts of the bogs. 

 Many borings have been made in all of these bogs to a 

 maximum depth of ten feet, and the data obtained con- 

 firm the finding of Burns (1) and indicate that the condi- 

 tions he reports as to greater depths would hold good 

 here also. 



DESCRIPTIONS OF INDIVIDUAL BOGS 



In many ways the most interesting bog is the one lo- 

 cated on Cedar Lake and numbered 1 in the first report 

 (4), as it is small in relation to the size of the lake and 

 is evidently very immature. (Fig. 2.) On the open edge 

 in the lake it is in the first bog stage, that of the quaking 

 mat, and the shrub and tree stages are only beginning to 

 appear. The bog mat is only about 100 yards wide, and be- 

 tween it and the shore is a swamp zone of about the same 

 width. (Fig. 3.) The depth of the water gradually in- 

 creases from the shore to the edge of the bog mat where 

 it is about 6 feet, and from there it rapidly deepens, going 

 beyond 10 feet in a short distance. Soundings beyond 

 that depth have not yet been taken, but according to local 

 opinion the lake is very deep just beyond the edge of the 



