INVESTIGATIONS IN MINNESOTA AND NORTH DAKOTA. 349 



the .south has suffered more from erosion, deep ravines and waterways 

 having- been cut through the drift, and in places touch bedrock. Big 

 Stone Lake is from 35 to 38 miles long and from 1^ to 2 miles wide. 

 The lake lies in more curves than Traverse and is less regular in width. 

 It exceeds Lake Traverse in depth, its maximum depth being 35 feet. The 

 bottom is of sand, and in some places a few inches of mud, strewn with 

 bowlders of various sizes. The temperature of the water at surface and 

 bottom is practically the same, owing to the frequent winds that stir 

 the water to the bottom. This body of water is subject to less fluctua- 

 tion in depth than Lake Traverse, on account of the outlet, which the 

 latter does not possess. 



The water contains but little mineral matter and is always clear and 

 fresh. The lake is said to be supplied with water from large springs in 

 the bottom, but nothing of the kind was observed, though several fine 

 springs along the eastern shore were visited. Besides the springs and 

 the direct surface drainage from a comparatively small area, the lake 

 receives the inflow from Little Minnesota River. The banks, which for 

 the most part are of the same slope and are almost continuous with the 

 higher hills, are composed entirely of drift material, no outcrop occur- 

 ring except at the foot of the lake. The shore is skirted with a narrow 

 belt of small timber that offers protection and shade. There is very 

 little vegetation in the water. Around the inlet and outlet are a few 

 acres of rushes, and these are bordered by a small area of submerged 

 vegetation. 



The lake is covered with ice during the winter, though it never 

 freezes to the bottom. Fish food, such as water insects, larvie, crusta- 

 ceans, and mollusks, is not as abundant as in Lake Traverse, yet the 

 supply is apparently sufficient. Two species of water-snail are common, 

 and a few shells of Anodonta were observed. It was also reported that 

 these bivalves were numerous about certain islands in the lake. 



The young of Catostomns teres nud Moxostomamacrolejndotnm, together 

 with Percopsis guttatus and a few species of Utheostoma and N'otropis, 

 were also common. 



The lake is well stocked with several varieties of good food-fishes, 

 foremost among which are pickerel {Luems lucms), bass {Micropterus sal- 

 moides), wall-eyed pike [Stizostedion vitreum), rock bass {AmbJoplites 

 rupestris), and crappie {Pomoxis sparoides). 



The pickerel is one of the most abundant species ; specimens weighing 

 from 8 to 12 pounds are often obtained. It is easily taken with the hook, 

 almost anything that will satisfy its voracious appetite or attract its 

 attention serving for bait. The large-mouth black bass is the favorite 

 of the angler, since much more skill is required in its capture. Almost 

 any bait will suffice to take this species here, but the young of Gar- 

 piodes velifer, li to 2 inches long, and Fundulus diaphanus, of about the 

 same size, are found most frequently in bait buckets, while the smaller 

 species of Pimephales and Utheostoma are not infrequently used. 



