SURFACE FEATURES. 33 



purpose of indicating more correctly, the general contour of 

 surface. 



It will of course be borne in mind, that diagram profiles of 

 this kind cannot be drawn so as to show the natural propor- 

 tion of the distance to the height, because the actual height 

 of the highest elevations of any region bears so small a pro- 

 portion to the distance across it. Therefore due allowance 

 must be made for the great apparent inequality of surface, as 

 shown in the diagrams, necessarily consequent upon repre- 

 senting the distance upon a much more reduced scale than 

 the height. 



Taking into view the facts that the highest point in the 

 State is but a little more than twelve hundred feet above the 

 lowest point; that these two points are nearly three hundred 

 miles apart, and that the whole State is traversed by gently 

 flowing rivers, it will be seen that in reality the State of Iowa 

 rests wholly within, and comprises a part of, a vast plain 

 with no mountain or hill-ranges within its borders. 



Peihaps a still clearer idea of the great uniformity of the 

 surface of the State, may be obtained from a statement of the 

 general slopes in feet per mile, from point to point in straight 

 lines across it. 



The following table of general slopes are approximately 

 correct: 



Table of Slopes op the General Surface op the State. 



From the N". E. corner to the S. E. corner of the State... .1 foot 1 inch per mile. 



From the N. E. corner to Spirit Lake 5 feet 5 inches per mile. 



From the N. W. corner to Spirit Lake 5 feet inch per mile. 



From the N. W. corner to the S. W. corner of the State 2 feet inch per mile. 

 From the S. W. corner of the State to the highest ridge 



between the two great rivers (in Ringgold county) ... .4 feet 1 inch per mile. 

 From the dividing ridge to the S. E. corner of the State. .5 feet 7 inches per mile. 

 From the highest point in the State (near Spirit Lake) to 



the lowest point in the State (at the mouth of Des 



Moines river) 4 feet inch per mile. 



Thus, if it were possible to reduce the surface of the State 

 to a perfect plain, preserving only the general slopes as just 



