236 



The pen sketch phite No. 1 gives some idea of the appearance of 

 one of these benches (see pen sketch section 32, Washington Township). 

 Plate YI shows beyond the trees a side view of one of the spur-like ex- 

 tensions of a bench occuiTing in section 4. Eloomington Township. (See 

 contour map No. III. which also shows position of the partly buried head- 

 land.) 



No. 1. Pen Sketch of Attached Spurs and Benches. Section 32, Washington Township. 



Post-iihicidl Histonj. Since the close of the laking stage Bean Blossom 

 River has developed a meandering course on its broad floor. Only in 

 the narrowest sections of the valley has it succeeded in spreading its 

 meander belt across the entire floor. For the most part it keeps to the 

 west or south side of the valley, and yet still assumes a meandering habit 

 for considerable stretches. In other words, the stream does not fit the 

 prcxnit dimensions of the broad valley, which accordingly must liave been 

 brought about by other conditions than that resulting from lateral cutting, 

 by a mature stream. Cross sections of the valley at its broadest places 

 reveal a slight curvattire of surface in the center and occasional abandoned 

 meandering channels. This slight variation from a plain surface suggests 

 flood plain construction. Whether this constructive work antedates the 

 glacial episode of Bean Blossom is not certain, but it would seem from 

 the data at hand, that the present post-glacial Bean Blossom has not had 

 time or the alnlity to do much constructive work since pleistocene time. 



YouiKj ^'(tU(■j|H. Traversing the steepest slopes of Bean Blossom, are to 

 be found numerous Y-shaped valleys, with remarkably steep channels, 

 ending their lower course at the point of intersection of the valley floor 

 with the adjacent slope. In all cases small alluvial fans are built on the 

 valley floor with their apex projecting but a few feet or yards at most 

 beyond the mouths of the young valleys. In none of the observe<l cases was 

 it found that the level of the valley- floor would extend into the mouth of 

 the young valley. It is therefore believed that the greater part of the cut- 

 ting of these young valleys may date subsequent to the preglacial filling. 

 The fact that alluvial fans and not deltas with steep outer edges and 

 flat tops occur at their mouths, suggest that they have been constructed 

 since the laking of the valley, and hence are regarded post-glacial. 



