12 DIMINISHED FLOW OF ROCK RIVER. 



The glacial drift on the surface allows a very free percolation of the 

 water. The sandstones underneath are also fairly pervious, while the 

 limestones and shales offer no serious obstruction. The geologic con- 

 ditions, therefore, may be said to be very favorable to a sustained and 

 ample flow of the river. 



EXTENT AND CHARACTER OF THE ORIGINAL AND THE PRES- 

 ENT FORESTS OF THE WISCONSIN DRAINAGE BASIN. 



This region at the time of its first settlement some sixty years ago 

 was extensively covered with forests, which, like those now standing, 

 were composed chiefly of hardwood species, including the Bur, Black, 

 Red. and White oaks. Basswood, Hard Maple, hickories, elms, and 

 ashes. On swampy ground grew Tamarack. White Cedar, spruce, 

 and willow. (PI. IV, figs. 1 and 2.) The total area of the forest at 

 that period may be estimated conservatively at 75 per cent. Allow- 

 ing 5 per cent for water surface, this would leave 20 per cent to be 

 divided about equally between prairie land and the low, marshy mead- 

 ows bordering the creeks and small streams. 



Since the settlement of the region some marked changes in the soil 

 cover have taken place. A large part of the forest has been removed 

 and the land brought under cultivation. Most of the prairie lands 

 have also been converted to agriculture, and many swamps and sloughs 

 have been drained and tilled. A considerable part of the 10 per cent 

 of marsh land, however, still remains. The proportion of land types 

 and water surface is estimated as follows: 



Per cent. 



Forest 30 



Cultivated land 57 



Swamp.- and uncultivated meadows 8 



Water surface 5 



In some sections — as. for instance, in the western part of Dane 

 County — the proportion of forests has increased since the time of set- 

 tlement: in others it has materially diminished. This diminution is 

 not always noticeable, because narrow strips and small wedges of tree 

 growth sometimes obstruct the A^iew across the low, undulating coun- 

 try and hide the extensive fields beyond, thus making the land appear 

 more heavily wooded than it is. 



Not only have the wooded areas diminished, but significant changes 

 have taken place in the conditions of growth. Originally the forests 

 contained a natural undergrowth of herbs, moss, tree seedlings, and 

 shrubs, which preserved the moisture and aided in the formation of a 

 rich, receptive mold. Some of the forests still retain this natural sur- 

 face growth, but many of the farm woods have been given over to 

 pasturage and have run to a dense matting of grass. 



