conditions under which the Dust Bowls have arisen in America or the soil drift taking 

 place in Southern Australia. If, however, we trace all categories of erosion back to 

 their origin or commencement it is possible to show in most cases that in this over 

 utilisation of the resources available, with the consequent upsetting of Nature's bal- 

 ance, a stage was, with few exceptions, always rea-ched at which the factor which 

 governs all production and life, the water supplies, commenced to become intermittent. 

 One way or the other this stage must have made its appearance. 



Under excessive utilisation of the soil then, the rainfall supplies in the region 

 fall into a delicate stage of oscillation,. It has been mentioned above that the first 

 decreases noticeable to man in the local water supplies show themselves in a lowering 

 of the water table in the soil owing to a decrease in the water in springs or their 'drying 

 up', including the wells, the drying up of streams in the hot months of the year, and the 

 lowering of water levels in the rivers. These partially precede the 'falling off in the 

 rainfall supplies. Man's life is short, his official service life shorter still, these gra- 

 dual manifestations occur almost imperceptably, though the speed is now- a- days much 

 accelerated, and long periods have passed before the balance delicately dropped on the 

 wrong side and man's chance of repairing the damage done is gone — for the desert or 

 conditions of aridity have won. 



What of the present day? The world has been shocked at the appaling conditions 

 which have been produced in the Dust Bowls in the United States and Canada in a brief 

 half century of over- utilisation of the soil assisted by all modern developments. And 

 yet whether it is a result of fifty years or thousands of centuries the outcome is the 

 same and the dangers are the same whether it be on the southern edge of the Sahara 

 where sand penetration assists desiccation, the Creeping Desert in the Sudan, the level 

 country at the foot of rapidly eroding hill ranges, the periphery of the Dust Bowls in 

 America, or the confines of the soil drifts forming desert in Australia; and also the 

 danger to the neighbouring agricultural or pastoral country is the same, namely the ex- 

 tension of the existing destroyed regions over their boundaries owing to gradual further 

 desiccation, dust storms and so forth. It is in these neighbouring lands that the inter- 

 mittent rainfall stage has been reached and man is called upon to make his effort to 

 restore the balance of aforetime before it is too late. 



Mr William Vogt is well known as the author of Road to Survival. He is a member 

 of the Chief Conservation Section of the United States Forest Service and has spent 

 nine years studying forests and forestry conditions in South America. He prepared a 

 memorandum for a Sub- Committee of the Forestry Section of F.A.O. which met in 

 Geneva in August 1947. His memorandum showed that against generally accepted 

 opinions amongst foresters, the Latin American Republics do not hold the enormous 

 forestry resources they were supposed to. He bases his reasons on the physical geo- 

 graphy of Latin America and the pattern of human settlement. The tropical lowlands 

 are not desirable for human settlement owing to prevalent diseases ; also a high pro- 

 portion of the area is unsuitable for agriculture because of excessively concentrated 

 rains that leach minerals from the soil, long blistering dry seasons that thoroughly 

 desiccate the vegetation once the forest has been cleared, and because high tempera- 

 tures tend to oxidise very rapidly organic materials in the soils. It is not at all un- 



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