270 FOEESTRY IN THE CROWN COLONIES. 



The prevailing rock is gneiss, whicli on decay gives a clay soil 

 of considerable depth. In the gneiss, bands of hard crystalline 

 magnesian limestone are common. Alluvium is found in all the 

 larger valleys. In the north, the Jafina Peninsula is post-tertiary, 

 consisting of marine Hmestone. Graphite is mined in the south- 

 west, also gem stones. There is no coal. 



Soils are mostly gravelly and shallow, but in the wet zone, 

 and especially in valleys, they are often rich and deep. They 

 have been much impoverished by long continued shifting culti- 

 vation. Rich soil eminently suited for agriculture is still found 

 in Jaffna. 



The Climate is greatly influenced by meteorological phenomena 

 in South India. There is no definite summer and winter, any 

 differences being due to the monsoons. During May to September 

 south-west winds prevail, and from October to April north-east 

 winds, rain coming from both directions. During the south-west 

 monsoon the mountain zone and the south-west of the island get 

 most of the rain, while the plain to the north and east is dry 

 and hot ; during the north-east monsoon the eastern lowlands 

 are watered and also the mountains. The rainfall varies between 

 20 and 200 inches ; the driest parts are situated in the north-west 

 and south-east. 



2. Main Types of Forest Growth. 



Ceylon foresters distinguish three main zones : — 

 (1) The Mountain Zone above 4,000 feet, comprising some 

 4,000 square miles, with a rainfall between 75 and 200 inches. 

 Above 5,000 feet, all forests are reserved, and no alienation of land 

 will be permitted in future, but in the past most of the area has 

 been devastated by tea, coffee and shifting cultivation. During 

 recent years about 130 square miles of forest have been re-estab- 

 lished. The zone is divided into two sub-zones : — 



(a) The Mountain Sub-zone proper. — The trees in this zone have 

 short, crooked and gnarled stems, owing to continued 

 exposure to wind and rain. The prominent species are 

 Rhododendron arhoreum, Calophyllmn trapezifolium and 

 Walkeri, Michelia nilagirica, Eurya japoniea, Gordonia 

 zeylanica and speciosa, Elwocarpus zeylanicus and other 

 species. Eugenia revoluta, assimilis, and others ; Sy?n- 



