58 THE U. S. GEOLOGICAL SURVEY 



Illustrative of the type of investigation undertaken by the 

 Survey in this direction are the continuing investigations of 

 the problems of flood prevention and of reclamation of marsh 

 and swamp lands, and the special investigation of the hy- 

 draulic mining debris problem. The investigation last men- 

 tioned, one of the most extensive and original of those made 

 in this field by the Survey, was undertaken at the request of 

 the California Miners' Association with a view to devising, 

 measures whereby the interests of agriculture and navigation 

 in the streams carrying mining debris could be harmonized 

 with those of the placer mining industry. The investigation 

 by the Survey, which extended over more than ten years, in- 

 volved research in the existing literature on the subject, 

 laboratory study of the laws of transportation of detritus by 

 running water, and a field examination of the entire course of 

 the Sierra Nevada River. The report of this investigation, 

 which was published in 191 7, recommends a cooperative con- 

 trol by all the major users of the Sierra's water whether for 

 mining, irrigation, or power development. 



Examination Under Act of March 1, 1911, of Land Pro- 

 posed to be Purchased by the Government for Protection 

 of Navigable Streams. The act approved March 1, 191 1, 

 known as the Weeks Act, which provides for the acquisition 

 of land for the purpose of conserving the navigability of 

 navigable streams, imposed a new duty on the Geological Sur- 

 vey. The lands to be purchased must be selected by the Na- 

 tional Forest Reservation Commission, but under section 6 

 of the act they may be purchased only after the Geological 

 Survey has examined them and submitted a report on them 

 to the Secretary of Agriculture "showing that the control of 

 such lands will promote or protect the navigation of streams 

 on whose watersheds they lie." The law thus places upon the 

 Geological Survey the responsibility of determining the funda- 

 mental question whether the control of any specific tract of 

 land will promote or protect navigability, and stipulates that 



