THE HISTORY OF BOYER VALLEY* 



JAMES H. LEES 



One of the largest streams of the Missouri slope in Iowa, and one 

 of much importance in its influence on topography is Boyer river. 

 This streams takes its rise in the Kansan uplands south of Storm 

 lake, flows a little east of south across Sac county past the town of 

 \Vall Lake where it turns abruptly southwest. In this direction it 

 crosses Crawford county, which it divides into practically equal 

 parts. In its course across Crawford county Boyer valley is of the 

 normal mature type but in southern Sac there opens into the valley 

 from the northeast a broad sag which extends southwestward from 

 Wall Lake. Digitate alluvial plains also- extend several miles up the 

 valley of the Boyer above the mouth of this sag and up the valleys 

 of two tributaries from the eastern flank of the high ridge east of 

 Odebolt. The flat undrained sag, although it is two or three times 

 as wide as Boyer valley at Herring or Boyer, is nevertheless a 

 direct continuation of it. On the other hand the present course of 

 Boyer river north of the sag is out of line and out of harmony 

 with the valley below. (See figure 122.) 



While, as will be explained below, Boyer valley in Craw^ford 

 county and in southwestern Levey township of Sac county is flat- 

 floored and steep-sided, above the junction with the sag the valley 

 has a sloping floor and widely flaring walls. The two profiles across 

 the valley given herewith will make this more clear than words can 

 do. (See figure 123.) 



In strong contrast also to the valley in Crawford county is the 

 character of the sag in the vicinity of the town of Wall Lake. Its 

 floor is almost perfectly flat and its sides slope rather gently away 

 to the upland, especially east of Wall Lake. West of here they are 

 somewhat steeper and higher, in the vicinity of the valley of Boyer 

 river and of the high ridge west of the upper Boyer. 



What seems to be the most reasonable explanation of this unoccu- 

 pied sag is that it is a fragment of an ancient Boyer valley which 

 once included the basin of Wall lake, or at least a part of it, and 

 possibly Indian creek. An arm of the sag extends to the southeast 

 as far as Carnarvon and may represent the lower part of another 



►Published by permission of the Director of the Iowa Geological Survey. 



