87 



I. Rivers. 



Two elements a. Changes in climate and altitude. 



b. Infli3.ence of physiograph7 on the river/flora. 



In a typical river there are four sta^-es Miss. River. 



1. Tlie ravine stage. 



2. The U-ahaped valley. 



3. The Poof plain. 



4. The Cresoentlc lakes or Ox-bows. 



Flora in all regions very different. The beginning of a river is 

 retrogressive. If a river eats back in a v/ooded coixntry, we shoiild 

 find a ravine flora replacing the forest . 

 •nevelopraent of flood plains. 



Great area of rich soil deposited by the river in its constructive 

 stage. In the destructive stage, the flora will retrogress ; in 

 the constructive, the progressive stage. 

 Lagoons or umlrained swamps. 



