CAUSES OF THE WANT OF TREE GROWTH. 7 



other situations, where the fires can, and do, come in 

 among them, that this theory can hardly be accepted 

 as altogether satisfactory. We therefore believe it to 

 be due to certain peculiarities of climate more than to 

 any other cause. Dry and cutting winds, prolonged 

 droughts, the porous nature of the soil, and consequent 

 scarcity of surface water, probably all contribute to 

 produce this result. The erection of buildings, fences, 

 and other shelter, and the fostering care of man, as 

 soon as the country is settled, seem, however, as we 

 have said, sufficient to cause trees to grow where 

 none were ever known to grow before. 



But the circumstance which seems to point most 

 strongly to some climatic cause, is the fact, that the 

 neighbourhood of the ocean, and the consequent pre- 

 valence of an indraught of water-bearing winds, deprived 

 of the exceedingly dry and cutting nature which char- 

 acterizes the land breezes, generally has the effect of 

 causing the plains country to disappear, and a land of 

 forests to take its place, not only on the seaboard, 

 but sometimes for a considerable distance inland, in 

 regions which further back consist of entirely open 

 plains. A notable instance of this is found on the 

 eastern seaboard of the United States, the whole of 

 which was formerly a great forest country which ex- 

 tended very often for a great distance inland, and 

 then suddenly from some unexplained cause the forest 

 country ended, and the prairie or plains country took 

 its place, and extended, with almost unbroken sequence 

 to the Rocky Mountains. The same thing is seen on 

 the Pacific coast, and also to a great extent in South 

 America; except in saline districts the "Pampas" 

 rarely reach the coast. In South Africa, and Australia, 



