414: GEOLOGY OF CENTRAL WISCONSIN. 



Lakes Michigan and Superior — along its northern edge, within thirty 

 miles of the latter lake. The waters which fall upon it are shed in 

 four different directions: to the north, into Lake Superior; to the 

 southeast, into Lake Michigan; to the south, into the Wisconsin^ 

 which ultimately reaches the Mississippi; and to the southwest directly 

 into the Mississippi. The northward streams, which interlock on the 

 summit of the divide with those flowing southeast, south, and south- 

 west, and descend in a distance of thirty miles nearly a thousand 

 feet, are entirely without the region at present under consideration. 

 Of the streams flowing sonthwestward, only the Black river drains 

 any considerable portion of the region, whilst the southeasterly streams 

 are mostly outside of its limits. Some of the latter pass directly to 

 Lake Michigan, whilst others concentrate into the stream known as 

 the Wolf, which, after leaving the area of crystalline rocks, takes a 

 southerly course until it meets the northward flowing Fox. The two, 

 uniting, pass through Lake Winnebago northward to Green Bay. 

 The systems of the upper Fox and of the Rock, though less immedi- 

 ately under the influence of the Archsean watershed of the north part 

 of the state, are still directly aifected by the geology of the regions 

 they drain, the M^aters of the upper Fox being shed to the east by the 

 high sandstone and drift region of western Marquette and Waushara 

 counties, and to the north by the high limestone belt which runs 

 southwestwardly through Green Lake and Columbia, whilst the tribu- 

 taries of the Rock river are shed southeastward by the same limestone 

 belt. Although traced thus directly to other influences, the drainage 

 areas and general surface slopes of the southern half of the state are 

 still in some degree ultimately attributable to the position and shape 

 of the Archaean nucleus. Whilst the southern region retains the gen- 

 eral slope southward of the crystalline rocks in the north, it also shows 

 the same eastward and westward slopes from a central north and south 

 line. This seems without doubt to be due to the continuance, beneath 

 the Paleozoic accumulations, of the ArcliEean mass with the same sur- 

 face structure as on its exposed portions, i. e., a central north and 

 south crest line, itself sloping southward, from which there are east- 

 ward and westward slants. 



Of the whole area of the Central Wisconsin district, the Wisconsiu 

 drains about 160 townships, including the eastern part of Clark, nearly 

 all of Marathon, a small part of eastern Jackson, nearly all of Wood 

 and Portage, all of Juneau, nearly all of Adams, all of Sauk, about 

 half of Columbia, and a few towns in northwestern Dane; the Black 

 river drains about 41 townships, including about half of Clark, nearly 

 all of Jackson, and a small area in the western part of AVood; the 



