ACTIVITIES 67 



The principal purpose for which the power of withdrawal is 

 now exercised, besides that of classification, is that of reserv- 

 ing from alienation public lands of special value, for the dis- 

 position of which Congress has made no adequate provision. 

 At the present time oil, gas, potash and phosphate lands, and 

 water-power and reservoir sites are being withheld from entry 

 pending legislation. Some of the tracts involved have been 

 thus withheld from entry since 1908. 



The power of withdrawal may also be exercised to create 

 permanent reserves in the public lands. Thus, several so- 

 called public water reserves have been created in the great 

 semiarid grazing areas of the West for the protection of the 

 public range. In addition large petroleum reserves have been 

 set up to insure an adequate supply of fuel oil for the Navy. 



The determination of withdrawals, whether permanent or 

 merely pending legislation, obviously requires an examination 

 and classification of the lands to be reserved in the same man- 

 ner as if the lands were to be thrown open to entry. 



Under present practice, the work of investigation and evalu- 

 ation carried on by the Survey is of two distinct kinds — the 

 one the systematic and comprehensive examination and classi- 

 fication of large areas, the other merely that of rendering to 

 the Land Office reports upon particular cases before it. 



Systematic Classification. In the systematic classification 

 of an area there is generally sought to be determined not the 

 classification of each tract under each of the land laws but 

 only under some particular provision of law, or for some spe- 

 cific contemplated withdrawal. Thus, the examination of an 

 area may be undertaken solely to determine which of the 

 tracts involved are phosphate lands. It may thus be found 

 necessary, from time to time, to reexamine and classify, with 

 respect to a particular provision, an area already examined 

 one or more times for classification with respect to other pro- 

 visions. 



Up to the present time, systematic classifications have been 

 attempted of coal, oil and gas, phosphate and potash lands, of 



