682 PAUL MacCLINTOCK 



by Black Earth and Halfway Prairie creeks. The surface of this 

 area is gently rolling and marked here and there by patches of low 

 sand dunes. This terrace level extends eastward into Black Earth 

 and Halfway Prairie valleys while the two intervening shorter 

 valleys have this high fill only at their very mouths. This relation- 

 ship is of importance in connection with the problem, later to be 

 considered, of the age of the terrace. 



From Mazomanie for a distance of 30 miles to the west, the 

 upper part of the valley train has been entirely removed from the 

 main valley. The terrace level is, however, present in most of the 

 tributary valleys; notably Blue Mounds, Wyoming, Otter, Pine, 

 Eagle, and Kickapoo creeks. But there are several tributary 

 valleys (see Fig. i) lacking this terrace level, a fact whose signifi- 

 cance is later to be considered. 



The remnants of this level, the high Wisconsin terrace, are 

 again found in the main valley near Muscoda and Blue River where 

 the bench is protected by a subjacent ledge of sandstone against 

 which the river is at several places flowing. At Boscobel a large 

 terrace remnant lies against the south wall of the valley. In these 

 latter terrace patches the material is smaller in size and contains 

 iewer limestone pebbles than farther up the valley. 



4. Twelve to 1 5 feet above the Wisconsin River flood-plain and 

 extending short distances up the valleys of many of its tributaries 

 there is an extensive sandy terrace — the low Wisconsin terrace. 

 From the terminal moraine at Prairie du Sac to Wauzeka, a distance 

 of 65 to 70 miles, it is nearly continuous in the main valley on one 

 side of the river or the other, while from Wauzeka to the Mississippi 

 it occurs only in small detached areas. Remarkable uniformity in 

 height above the river is one of its most notable characteristics, for 

 the variation is not more than a foot or two throughout the whole 

 distance. A second notable feature is that the material, where 

 seen in shallow cuts, is uniform in size and constitution through 

 the whole length of the valley, being mostly sand with small pebbles 

 scattered rather uniformly through the mass. The surface of this 

 terrace is in general very flat, but in detail it is seen to have irregu- 

 larities produced by the wind, such as sand dunes and "blow- 

 holes." Considerable dune areas are found in the neighborhood 

 of Lone Rock and Spring Green. In fact, the whole terrace is so 



