81 



Leot-are 10^ AitCT!.st 9. 1900 . 



I. ProgrrQRRivq Series (Youth to maturity. 



(.Poverty to wealth. 



A. Towards water levftl Xerophytio to Mesophytio. 



1. Hills ja. Chemical aM Physical Mture. 

 \Jo. Direction of Slope. 



Crustal riioveraents riiay have the sar.ae or opposite effects as 

 physiographic factors. An upward crustal raoveraent in a swanp 

 will have the same effect as the physiographic. A country-s 

 development may "be traced from youth to maturity, as v/ell as from 

 poverty to wealth, a condition due to the accumulation of // huriis. 



The Flora at the start on a hill or mountains must he xerophytic 

 Erosion is always tending to wear a hill down to level, rounding 

 the edges first. The slope being different, by drainage changeB, 

 the rocks are worn into finer materials, and as plants die, humis 

 :■ -accumulates. Changes in shape bring abo\xt different conditions 

 for plant life. The principal changes will be 



1. Less exposure. 2. Ilore water. 3. Finer soil. 

 4. Accumulation of humis. 



From these differences vegetation will soon change from xerophy- 

 to raesophytic. In diggijig throixgh a hill we find the water level, 

 no sudden change, but the amount of water in the soil gradually 

 increases as we pass downward. 



Tji 7-ls (a) Chemical and Physical Factors . 

 1. Sand and gravel. (Karnes — glacial). 

 V/j + i-. vao-nir'fi to the nature of the soil Karnes are the same as sand 



