VALLEYS OF SOLUTION IN NORTHERN ARKANSAS 49 



exists which adds the work of corrasion to that of solution, the 

 latter occurring mainly on the valley slopes above the stream 

 bed. As this work goes on and the stream bed continues to be 

 reduced more and more below the average level of groundwater, 



Fig. 2. 



the stream grows in size, and in time, by meandering, is able to 

 produce a wide valley. 



The point at which the valley cuts into groundwater of course 

 varies with the seasons, but on the whole it is moving up the val- 

 ley because of the differential solution brought about by the 

 large amount of groundwater moving down the slope from 

 either side and meeting beneath the bed of the valley. 



