530 STEVENSON— FORMATION OF COAL BEDS. [November 3, 



spite of the excessive rainfall. During November of 1909, the rain- 

 fall in the mountains of Jamaica was of unprecedented volume, there 

 being at one locality 120 inches in eight days, while in others there 

 were 20 to 30 inches within one day. Banana plantations, with 

 unprotected soil, were washed down the hills and the plants became 

 projectiles with which the flood destro}"ed vegetation on the low- 

 land; but the forest remained almost uninjured and the litter cover- 

 ing the surface around the trees was practically undisturbed. Where 

 the land was protected by trees, damage was confined to gullies 

 digged by fallen trunks pushed forward by the water. These gullies 

 widened in soft materials and trees, tumbled into the torrent, were 

 carried to the lowland, where they were deposited, pele mele, with 

 mineral matter on the cultivated land. Nowhere in the whole area 

 w^as there evidence that rainfall did any serious injury to either 

 forests or the forest litter. 



Cornet's'-* observations in the Congo region are to the same efifect. 

 Where the dry season is prolonged, plants are practically dried bv 

 desiccation, so that the first rains do great damage ; in such localities, 

 this is so serious that vegetation cannot re-establish itself. Rut, 

 near the equator where rains are almost constant, the forest quickly 

 reoccupies areas which man has cleared. Even in regions with a 

 long dry season, the bottoms of the valleys, owing to dampness, be- 

 come forested and that puts an end to the action of the wild waters 

 — it may cause even diversion of streams. Clearing of forests lays 

 the humus open and it is carried ofi^ to be spread elsewhere, there to 

 enrich the soil. This actually occurs in many valleys, giving what 

 Dupont has termed tcrroioir; but in the broad alluvial valleys, where 

 humidity prevails throughout the year, vegetable detritus accumu- 

 lates on the surface and gives a formation of humus sitr place. 



It matters not where one looks, the conditions are the same. 

 Geikie,"^ familiar with the Highlands of Scotland, where bogs in the 

 heath stage cover great areas, says that the surface of a district pro- 



' J. Cornet, " Les depots superiiciels et I'erosion continentale dans le 

 bassin du Congo," Btill. Soc. Belize de Geologic, Vol. X.. 1897, Mem., pp. 

 44-116. 



'".A. Ceikie, "Textbook of Geology," 3d Ed., London, 1.S93, p. 475. 



T28 



