FORESTRY SURVEY 199 



The eastern zone of brown silt loam was originally 

 prairie that the forest gi'owth had usurped. Here a 

 splendid xerarch-mesophrtic forest occupied the land and 

 in its second-growth stage represented the passage of 60 or 

 more years. The red oak predominated, but there was a 

 rich intermingling of black cherry, red elm, pin oak, and 

 yellow-bud hickory. It was pre-eminently an oak growth. 

 On the very broad yellow-silt loam zone another forest of 

 almost pure oak prevailed, but here, on all the drier parts, 

 white oak predominated, and in the moister situations pin 

 or Hill's oak occurred. The ridge summit flat of yellow- 

 gray silt loam was very largely occupied by hazel, aspen, 

 willows, and the open, marshy grass lands having the 

 buffalo wallows before described. None of the trees in the 

 yellow silt hill were over 24 inches in diameter. The 

 growth on the flat was evidently of the Populus-Salix as- 

 sociation, and was so because of lack of drainage, the gray 

 silt forming hardpan. 



The narrow alluvium strip along Clear Creek was very 

 largely covered with bur oak. which everywhere in Jo 

 Daviess county characterizes the well-drained black silts, 

 and, as before stated, the junction of the Maquoketa and 

 Galena formations. A plentiful supply of water is one of 

 the evident requirements of this oak. Very typical pin 

 oaks (Q. cUipsoidalis Hill^ were rather common also and 

 occasional yellow-bud hickories (Carya cordiformis). 

 Growing on the narrow strip of stony loam were mostly 

 ironwood. white oak. pin oak. and shagbark hickory. 



A very marked result of the deforestation of this region 

 has been the gi-eatly lessened surface water supply. Orig- 

 inally, besides Clear Creek, there were at least six minor 

 brooks and 15 springs ; today there are none. Clear Creek 

 is only about one-fourth of its former volume and now has 

 very high flood periods. In periods of severe drouth no 

 soil moisture was found at times above the bedrock, which 

 is at a depth of 20 feet below the surface, and many 

 isolated clumps of trees had died, evidently from lack of 

 water or lowering of the water-table. Gi*ound-water, that 

 formerly stood from 2 to 3 feet below the surface, is now 

 down to a depth of 10 to 15 feet. 



