THE LOWER SILURIAN ROCKS. 581 



Further ideas as to this structure can best he ohtained by examination of the sections of 

 Plates XXn and XXIII, in connection with the map of Area E. In southeastern Lodi, 

 Arlington, Leeds, Hampden, southeastern Lowville. southwestern Otsego, and southern 

 Fountain Prairie, the country above the escarpment is generally rolling prairie, much of 

 it very high. Further north, in northern Otsego and Fountain Prairie, and southern 

 Courtland and Springdale, the prairie belt is broken by a belt of the ordinary oak tim- 

 ber. Still further north again, prairie spreads widely over the limestone country of Court- 

 land, Randolph, Springdale and Scott. Nearly all of the country east of the escarp- 

 ment shows a most excellent soil, being underlaid for the most part by limestone, which 

 is, however, frequently buried beneath much glacial drift. An exception would be those 

 portions of Fountain Prairie and Otsego where erosion has carried the surface into the 

 horizon of the Madison sand beds, the result being a loose, sandy soil, like that of the 

 regular Potsdam regions. The streams watering this district are mostly small, and all 

 flow eastward towards the Rook river. 



Immediately west of the limestone edge, there is an abrupt descent of 100 to 300 

 feet, and, beyond, a more gi-adual slope of 50 to 100 feet to the Wisconsin river. This 

 area has, in general, the character of a sandy plain, timbered with small oaks, with 

 marshes along the streams, and dotted here and there with isolated bluffs, 100 to 400 

 feet high, from a few 3CTes to several square miles in area, and generally sunnounted by 

 a capping of Lower Magnesian limestone. But very Uttle prairie is met with. Some 

 occurs in the town of West Point, including both low laud and limestone outliers. The 

 streams are larger than those on the east of the divide, increasiug in size as the escarp- 

 ment recedes from the Wisconsia. Spring creek, in Lodi, Okee creek, in southern De- 

 korra and northern Arlington, Rocky run, in northern Dekorra and Lowville, the 

 several branches of Duck creek, in Pacific, Wyocena, Springvale, Courtland and Ran- 

 dolph, and the Pox river in Fort Wktnebago, Marcellon, Wyocena and Scott, are the 

 principal streams. The towns of Lewiston, Newport and Fort Winnebago, west of the 

 Fox river, and north of the Wisconsin, are similar to the rest of this sand district in 

 many respects ; but are more roughened in surface, the northern portions of the two for- 

 mer rising up to the high land through wliich the passage of the Dalles is cut. 



West of the Wisconsin river we find the topography influenced primarily by the 

 quartzite ranges of the Baraboo, which have already been sufficiently described. For 

 our present purpose it is merely necessarj' to remember that they are two east and west 

 ranges, some twenty miles in length, uniting at both ends, and thus entirely enclosing 

 the low ground between them. They are made up of Archaean quartzite and quartz- 

 porphyry, but the country around and between them is all occupied by the horizontal 

 formations. Outside of the ranges in the towns of Caledonia, Columbia county, and 

 Fairfield, Merrimack, Prairie du Sac, and Sumpter, Sauk county, the country is in most 

 respects like the level sand district immediately east of the Wisconsin, showing in the 

 more southern portions a few limestone-capped outUers. Farther west, however, we 

 pass beyond the western limit of the glacial drift, and find the topography presenting 

 the usual marked change, being characterized by narrow ramifying ridges and valleys, 

 the former, in the more southern towns, commonly capped by the Lower Magnesian lime- 

 stone, but in the more northern formed entirely of sandstone. In the southern part of 

 Sauk county, immediately west from the drift hmit, the ridges are found frequently 

 worn into narrow, isolated crests, 100 to 200 feet high, and with frequent rock exposures, 

 constituting a very marked and peculiar scenery. Farther west, the ridges are broader, 

 and large areas of limestone occur on the liiglier levels. In the town of Westfield, west 

 from the ends of the quartzite ranges, the high ground continues, capped now by the Lower 

 Magnesian limestone, and forming the divide between Honey and Narrows creeks. 

 Honey creek enters the Wisconsin about five miles below Sauk City. Following it to- 

 wards its source, we find it, separating, in the northern part of the town of Troy, into 



