west and southwest faces of the outer knobs are treeless. This 

 lake is said to be 18 or 20 feet deep, but a careful exploration of 

 its bottom has not yet been made. 



The region to the southeast is rolling, with numerous kettle- 

 holes between ridges which were formerly well-wooded, but are 

 now partially cleared. The map shows the original extent of the 

 groves. 



The entire region between the Okoboji lakes is more or less 

 rolling, the eastern and southern parts being more elevated, 

 though not much broken, and mostly covered with prairie. The 

 hill southwest of Okoboji station rises about 55 feet above the 

 lake. Between Center lake and West Okoboji lake the surface is 

 somewhat broken, and kettleholes are frequent. A portion of one 

 of these is shoT^m in Plate VIII, fig. 2. Several dry knobs in this 

 part are still covered with native prairie flora. Northward, to- 

 ward the head of West Okoboji lake, these knobs and ridges be- 

 come more massive, and the highest rise over 100 feet above the 

 lake. 



Xorth of Center lake the surface is more or less rolling, with 

 broad depressions occupied by swamps and small lakes. The 

 groves shovTL around the small lakes lying north of the railway 

 are also located on, or in the shelter of, abrupt banks which reach 

 a height of 15 feet in some places. 



The region to the northwest and west from the head of West 

 Okoboji lake is mostly rolling upland prairie, with occasional 

 sloughs or kettleholes, and it is cut by the valley of the Little 

 Sioux, which is here bordered by rather gently sloping hills, and 

 is practically treeless. 



The region between West Okoboji lake and the Little Sioux 

 river is of the same general character, but contains a large num- 

 ber of kettleholes, some of which are represented on the map. 

 These kettleholes were formerly rich in marsh and aquatic plants, 

 but many have been drained, and the tramping of stock has 

 robbed them of their wealth of these plants, but some are still 

 presented, and well illustrate the" character of the interesting 

 marsh flora. Two of these, lying immediately west of the Look- 

 out, are shown in Plate YIII, fig. 1. 



The upper course of the valley of the main branch of the 

 Little Sioux is practically treeless, and the bordering hills are 

 not abrupt, but opposite Pratt lake the hills on the west side be- 



12 



