18 BOTANY OF LA SALLE COUNTY. 



/ 



IV. Clothing- a region with forest tends to diminish 

 floods, to create ponds and swamps to prevent exten- 

 sive washing- of slopes and to diminish landslides. 



For those who think, the above proposil ions require 

 no argument, (but all men do not think,) we will 

 therefore say, the land of a forest is covered each 

 autumn with a layer of leaves and rubbih forming- a 

 cloak as it were that absorbs and holds much water, 

 retards its flow over the surface and checks and regu- 

 lates evaporation; hence streams do not rise so fast in 

 a wooded region as in a naked one. The roots of the 

 trees bind the soil together, resist washing, and tend 

 to prevent furrowing. 



Already the effects of the removal of the forest may 

 be seen in the excessive washing of the denuded bluffs, 

 extensive landslides, the sudden rise of streams during 

 heavy falls of rain. In the meantime these lands pro- 

 duce little pasture and are of little value for agricul- 

 ture, as they are usually parched by droug-ht for two or 

 three months of the year and the surface is then dust, 

 the vegetation brown and dry. , 



With proper care these timbered tracts might be 

 made a source of regular income from their yield of 

 timber, a purpose for which they are well fitted 

 while as pasture or farming land they have little value, 

 not that grain and g-rass will not grow on them but 

 that they cannot be depended upon to produce crops 

 unless a supply of water can be made sure and this 

 involves irrigation and considerable expense at the 

 outset, besides protection from washing during heavy 

 rains and landslides during wet seasons and in spring. 



Tables of elevation of principal points in La Salle 

 County, most of these \Vere obtained directly from the 

 Chief Engineer of the railway on whose line the place 

 is located. 



