SOUTHEEN APPALACHIAN REGION. 



129 



These and other facts concerning the general climatic 

 conditions of this region are brought out in the acconi- 

 panying paper by Professor Henry of the United States 

 Weather Bureau, showing the records of temperature, 

 rainfall, and humidity at the stations of the Weather 

 Bureau between Lynchburg, Va., on the north, and Mont- 

 gomery, Ala., on the south, and from Salisbury, on the 

 east, to Knoxville, on the west. 



The entire region is characterized by extremely heavy ^^Heavy rain- 

 rainfall in very short periods of time, and owing to the 

 steep slopes and the absence of lakes, ponds, or marshes, 

 which could act as reservoirs and hold back the storm 

 waters, protracted heavy precipitation is followed by a 

 rather rapid increase in the flow of the streams, the rise 

 lasting generally for onl}' a few hours, and the stream 

 soon assuming its normal stage of flow. This is more 

 especially the case where there are forest clearings. Con- 

 sequently these violent rains, under certain conditions — 

 i. 6. , where rains are excessive and clearings extensive, or 

 where forest areas are burned over so as to destroy the 

 humus and undergrowth — give rise to floods which are 

 very destructive to property and which cause occasionally 

 the loss of human life. To a certain extent the forest acts 

 as a reservoir, for it keeps the soil porous, allows it to 

 absorb and hold the water for a time, and gradually gives 

 it forth in the form of springs and rivulets. Where the 

 areas have been deforested, however, the rain water forms 

 small but swift-flowing torrents down the sides of the 

 mountains, and quickly reaches the streams below. Deep 

 channels are cut in the mountain sides, and all of the top 

 fertile soil is carried off, leaving only the underlying clays, 

 which are of poor quality and do not yield to cultivation. 



After a storm the streams rising in the deforested areas 

 are extremely turbid with mud from the mountain sides, 

 while those from the forest areas are comparatively clear. 

 This erosion can be noted b}^ the most casual observer, and 

 it forms one of the greatest menaces to the region. The 

 soil is deep and fertile, as is shown by the splendid growth 

 of forest trees and by its y\e\d under the first cultivation, 

 but it is only a question of time, if the forests are wantonly 

 cut, when all of the soil and vegetation will be washed from 

 the mountain sides and nothing will remain but the bare 

 rock. 



These floods, due to protracted rains, are also destruc- 

 tive in strips of, valley lands bordering the streams in the 



*S. Doc. 84 — -9 



