THE FARGO CLAY LOAM. 5 



to 50 feet. These are bordered only by a few narrow areas of bot- 

 tom land, while the banks of the rivers usually rise steeply to the 

 adjoining plain. The tributaries to the major streams also occupy 

 steep-banked channels and are themselves joined by coulees and gul- 

 lies which constitute the off-flow channels of the surface water. Be- 

 tween the larger drainage lines there often exist areas 5 to 15 miles 

 wide which are unmarked by any water course. The highest parts 

 of these divides are commonly not more than 3 to 5 feet above the 

 lower areas. 



In elevation above tide level there is a narrow variation be- 

 tween the different areas occupied by the Fargo clay loam. The 

 lowest points undoubtedly lie along the boundary line between the 

 United States and the Dominion of Canada at an altitude of about 

 975 feet above tide. The highest altitudes within the area of the 

 Glacial Lake Agassiz rise to about 1,100 feet at its southern termina- 

 tion in the vicinity of Lake Traverse. The altitudes of the smaller 

 areas of the type, in the scattered minor glacial lakes of southern 

 Minnesota and of South Dakota, are quite variable, but usually range 

 from approximately 1,000 feet to less than 1,200 feet above sea level. 

 There is thus a marked uniformity in altitude and in the surface 

 topography of all portions of the type, with very little pronounced 

 relief and with practically no change of climatic environment due to 

 differences in altitude or topography. 



The drainage of the Fargo clay loam is frequently defective. The 

 natural drainage is well established only in the immediate vicinity of 

 the water courses and upon the crests of undulating divides between 

 these courses. The broad stretches of nearly level prairie which 

 occupy a considerable proportion of the territory covered by the 

 Fargo "clay loam are decidedly defective in drainage, not only be- 

 cause of their level nature and infrequency of water courses, but also 

 because of the stiff, moisture-retaining character of both the surface 

 soil and subsoil, accentuated in many instances by abundant accumu- 

 lations of organic matter through the deep surface soil. 



Erosion is not a serious problem over any considerable proportion 

 of the type. It is only along the margins of the deeper cut stream 

 channels and around the head waters of the coulees, which form 

 the principal tributaries, that active erosion is in progress. Never- 

 theless, some difficulty has been encountered in the establishment of 

 open ditches to perfect the natural drainage of the Fargo clay loam 

 through the deep cutting of drainage waters, accompanied occa- 

 sionally by the caving of the banks. Slight precautions in the estab- 

 lishment of grades of such ditches and in the protection of the banks 

 of natural drainage ways will be entirely adequate to counteract this 

 tendency. 



