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IOWA ACADEMY OF SCIENCE Vol. XXVI, 1919 



low and not well defined, but at the base of the willows we find a 

 large pool of cool water nearly six feet wide and three feet deep. _ 

 Just below this is the bridge shown in figure 13 and from there ■ 

 down to Station 3 there appears a series of pools and shallow water. 



Pig. 12." — Looking east showing clump of ti ees above spring at liead of Dry 

 Run. 



Fig. 13. — Looking west just below spring at head of Dry Run. 



The bottom through this area is mostly soft mud and gravel, but 

 there appear at intervals a few large bowlders such as arc shown in 

 figure 13. Below this area of pools and shallow water the stream 





