_Topography._--The South or main quartzite range, about 23 miles in length and one to four miles in width, rises 500 feet to 800 feet above the surrounding sandstone plain. Its slopes are generally too steep for cultivation, and are clothed for the most part with a heavy growth of timber, the banks of forest being broken here and there by cultivated fields, or by the purple grey of the rock escarpments too steep for trees to gain a foothold. With the possible exception of the Blue mounds southwest of Madison, this quartzite range is the most obtrusive topographic feature of southern Wisconsin. As approached from the south, one of the striking features of the range is its nearly even crest. Extending for miles in an east-west direction, its summit gives a sky-line of long and gentle curves, in which the highest points are but little above the lowest. Viewed from the north, the evenness of the crest is not less distinct, but from this side it is seen to be interrupted by a notable break or notch at Devil's lake (Plates V and XXXVII). The pass across the range makes a right-angled turn in crossing the range, and for this reason is not seen from the south. The North or lesser quartzite range lying north of Baraboo is both narrower and lower than the south range, and its crest is frequently interrupted by notches or passes, some of which are wide. Near its eastern end occurs the striking gap known as the _Lower narrows_ (Plate IV) through which the Baraboo river escapes to the northward, flowing thence to the Wisconsin. At this narrows the quartzite bluffs rise abruptly 500 feet above the river. At a and b, Plate II, there are similar though smaller breaks in the range, also occupied by streams. The connection between the passes and streams is therefore close.