OKLAHOMA ACADEMY OF SCIENCE 121 



South Canadian river for about three miles above and below the 

 Norman bridge. 



The South Canadian is a type of stream, very common to the 

 Great Plains country. It has a broad flat valley and a sand 

 choked bed vi^hich is usually much too broad for the amount of 

 water carried, but at times of flood it is sometimes completed 

 filled with water. In the humid regions, a sand choked stream is 

 considered an aggrading stream but in a stream like the South 

 Canadian which has such extremes of high and low water the 

 determination as to whether it is aggrading or degradding depends 

 on the amount of scour during high water compared with the 

 amount of fill at times of low water. Probably the only way this 

 can be accurately determined is by a series of observations extend- 

 ing over a number of years. While streams of this type are com- 

 monly spoken of as braided streams the South Canadian is not at 

 all times a braided stream. At times of high water 

 it fills its bed from side to side. At other times, if it maintains 

 the same volume for any considerable length of time, it soon ad- 

 justs itself so that it flows mostly in one channel. This is espe- 

 cially noticeable at times of low water. It takes on more of a 

 braided appearance at times when the water is rapidly rising or 

 falling. 



The valley of the river is nearly three miles wide at the 

 bridge. On each side of the stream are two terraces which appear 

 to be remnants of old flood plains. The highest one which is 15 

 to 20 feet above the present river bed is the older and is covered 

 with good soil and the trees and other vegitation are of the more 

 permanant type. The lower terrace is five or six feet above the 

 river bed. The soil of this terrace is sandy much like the present 

 stream bed and the prevailing timber growth is of sma'.l cotton- 

 wood. Remnants of old stream beds can be traced on both the ter- 

 races and especially on the lower one. About one and one-half 

 miles above the bridge and on the south side of the river is a rem- 

 nant of an old channel which at tim^es is a shallow lake more than 

 half a mile long and nearly half as wide. Upstream from the lake 

 a channel can be traced to its junction with the present stream 

 bed but its bottom is about four feet above the bottom of the pres- 

 ent stream so the lake receives water only at times of high water in 

 the river. Also about two miles below the bridge and on the 

 same side of the river are remnants of stream channels which con- 

 tain water m.uch of the time and at times of high water are fed 

 in the same way through narrow channels from the river. 



A marked difference between the South Canadian and streams 



