SURFACE FEATURES. 



37 



between the two great rivers, continues southward without 

 change of character through Ringgold county into the State 

 of Missouri; but southward from that point, in Adair county, 

 it is no longer the Great Watershed. From that point 

 another and lower ridge* bears off more nearly southeast- 

 ward, through the counties of Madison, Clarke, Lucas, and 

 Appanoose, and becomes itself the Great Watershed. Thus, 

 as one goes westward along the line of the Burlington and 

 Missouri Biver Railroad, or along the southern boundary of 

 the State, he passes the Great Watershed long before he 

 reaches the highest land between the two great rivers, and at 

 points that have more than two hundred and fifty feet less 

 elevation. The accompanying diagram, Fig. 1, gives a gen- 

 eral view of the drainage system of the state: 



Fig. 1. 



*The meaning of the word "ridge" as used here should not be misunderstood. The 

 ridges which constitute the watersheds of Iowa, are seldom sufficiently elevated above 

 the surrounding surface to be distinguished by the eye, and their presence is usually 

 recognized only by observing the direction of the drainage, or by actual leveling with 

 instruments. 



