PLATE LVIII. 



CASS COUNTY AND PART OF CROW WING, 1899. WARREN UPHAM. 



Only two outcrops of rock are known in this area. One is near the Todd county 

 line and the other is on Boy river, near the north side of T. 142-27. The rock of the 

 former is gray granite, rather fine grained, containing both white and flesh-colored 

 feldspar, and much epidote. Mica is scarce. In general this rock strongly resem- 

 bles that seen in Ward township, Todd county, and in Ashley, Stearns county, and 

 belongs to the Archean. It is crossed by two dikes of diabase, one being fifty to 

 sixty feet wide and the other thirty feet. One bears S. 50 E. and the other S. 70 E., 

 the latter being also the direction of a conspicuous system of joints. 



The other outcrop has not been seen by any officer of the geological survey, 

 and its characters are unknown. 



Cretaceous debris is found in the drift, including lignite, about the shores of 

 lakes Leech and Winnibigoshish, but in the general absence of Winnipeg limestone 

 pieces such Cretaceous cannot be referred for source to points toward the northwest. 

 It is to be inferred that this debris came from Cretaceous underlying the drift in 

 this county, or near adjacent to the north. 



Two belts of terminal moraine pass through Cass county, one lying south of 

 Leech lake, running in an east and west direction, and the other northeastwardly 

 from Wheelock to the Aitkin county line. Mr. Upham considers the former as a 

 continuation of the tenth or Itasca moraine, and the latter as a part of the ninth or 

 Leaf Hills moraine. 



There are some extensive plains of modified drift in Cass county, yet sometimes 

 these are broken by extreme undulations that vary from twenty to forty feet between 

 the hills and the valleys. Such drift is scattered to the southward from the morainic 

 belts. The later moraine sent such water-borne gravel and sand widely over the 

 central part of the county, and appears to have almost obliterated the characteristic 

 features of the next earlier moraine through an interval north of Gull lake. In these 

 gravel plains, as in others in counties further west, are isolated deep depressions in 

 which sometimes lakes exist. These isolated depressions, or kettle holes, are attrib- 

 utable to isolated masses of the glacier which lay in the way of the gravel-bearing 

 waters, and remained until the waters subsided. On melting, these isolated ice 

 masses left vacancies in the gravel plain which have not been filled. 



Long gravel ridges are found at various places. These are kames. They were 

 formed by streams that flowed between ice walls, sometimes for several miles, wash- 

 ing the drift that fell from the ice on either side and carrying away the clay con- 



