PLATES (PAGES) XXI AND XXII. 



MURRAY AND NOBLES COUNTIES, 18S4. WARREN UPHAM. 



These counties afford no rock outcrops. The drift consists almost wholly of 

 unmodified till, and seems to have a great depth. In the till are minor variations 

 to gravel and sand, which afford water in wells. There is also a gravelly plain in 

 Grand Prairie, southwestern part of Nobles county, which was formed by abundant 

 waters flowing from the moraine at the time of the earlier ice-sheet, spreading the 

 coarser materials of the drift over the lower lands. This gravelly deposit, and nearly 

 all the area of these counties, are now covered by a fertile soil. The adjoining areas 

 of till rise from forty to seventy-five feet above this plain. 



There is more or less gravel to be found also in the" hilly morainic belts which 

 cross these counties. These afford reservoirs for springs at lower levels, and serve 

 as sources to the creeks. The DesMoines river rises from such sources in the north- 

 west corner of Murray county. 



The western morainic belt, constituting the crest of the principal Coteau des 

 Prairies, rises, in its highest part, in Buffalo ridge, in Murray county, to 1,950 feet 

 above the sea, and it sustains an altitude of 1,800 to 1,900 feet through most of Cam- 

 eron and Chanarambie townships. Further south, through Nobles county, it has an 

 average maximum altitude of about 1,700 feet. The lowest land in Murray county 

 is in the northeast part of Holly, 1,250 to 1,300 feet above the sea, the extremes in 

 this county being separated, therefore, about 700 feet. The lowest land in Nobles 

 county is at the point where Jack creek crosses its eastern boundary, about 1,420 feet 

 above the sea, and 300 feet below the crests of the morainic belt. 



The eroded valleys are from fifty to seventy-five feet deep, and generally a half 

 or three-fourths of a mile wide. 



The terminal moraines which cross these counties denote the farthest limit of 

 the ice of the last glacial epoch, there having been a period of rest, and perhaps of 

 readvance, at the place where the eastern, or later, moraine lies. The drift which 

 lies further west and southwest, occupying Nebraska, Kansas and Missouri, was the 

 product of the earlier glacial epoch. It can be inferred that the till to the east of 

 the Coteau des Prairies was of later date than that to the west from the fact that 

 nearly all drainage courses flowing westward take their rise along the eastern margin 

 of the coteau and maintain deep channels through the coteau; while not one that 

 flows eastward rises in the western margin of the coteau. This gave the westward- 

 flowing streams an earlier date than the eastward. The latter could not begin till 



