Mohave County miner., 1916-12-16
HYDRAULIC MINING
 DEBRIS CONSTITUTES
 VEXATIOUS PROBLEM
fFrom Thursdsy.s paIly Minerl

A nOJaDle cOnIrlDuIlOn 10 SeOlOSlc literature in it's broadest relations has during this year been completed for publication by the United States geo. logical survey, department of the in- terior. The report, which will be is
 sued during the coming year, is en- titled Hydraulic Mining Debris in the
 Sierra Nevada" and represents an ex- tremely thorough investigation by
 Grove Karl Gilbert. To illustrate the
 scope of the investigation and of the report now completed: In a memorial presented to the president of the Unit
 ed States in 1905, the California Min CTS association, after emphasizing the contribution of placer and hydraulic
 mining to California and to the nation,
 expressed the conviction that a ra- tional application of the natural laws
 governing the deposition of sediment
 from torrential streams would permit
 both hydraulic mining and agriculture
 to be carried on in this region, not
 only without prejudice to each other,
 but to their mutual advantage. In the
 belief that the question was primarily geologic, as it involves the study of erosion and of sedimentation in the
 mining districts as well as in the lower valley regions, the association request
 ed that the director of the United
 States geological survey should be in
 structed "to undertake a particular
 study of those portions of the Sacra- mento and San Joaquin valleys affect ed by the detritus from torrential streams"
 The investigation then begun by Mir. Gilbert was planned to include a field study of the natural phenomena con nected with the problem and a labora- tory study of the laws of transporta- tion of detritus by running water. The results of this laboratory study have already been published in the surveys professional paper, 86-"The Trans portation of Debris by Running Wa ter"-and the report just prepared, which deals with the geologic and physiographic phases of the problem, presents the results of the completed investigation and contains conclusions much broader than the answers to the specific questions raised by the Cali fornia Miners association.
 This report, which will be published as professional paper 105, will rank as one of the largest contributions of the United States geological survey to geologic and engineering science and will also assist materially in solving this problem, which involves mining, agriculture and navigation. To make such an investigation eminently sue cessful, it has been necessary that the investigator should unite an aptitude for close observation and for logical with a habit of deter mining quantitatively as many as pos sible of the factors of the problem in hand. To his task Mir. Gilbert has brought these qualities in a marked degree with the result that his report is masterpiece wherein geology and engineering both contribute to the so- lution of a practical problem of the first rank. Especially important has it been that this subject should be viewed with the broad outlook of the geologist who appreciates the time factor that enters to so large a degree into any reaction of crustal change, erosion and sedimentation. The studies cover every phase of the subject, from the original source of the detritus in the Sierra Nevada to the possibility of its transportation through the Golden Gate to the Golden Gate bar, and in his broad treatment Mir. Gilbert has not only estimated the waste due to agriculture, grazing, roads and trails and mining and studied its movement seaward, but he has supplemented his observations and estimates with in- strumental surveys of impounded de- tritus as well as with measurements of tidal currents in the Golden Gate.
 The investigator appreciated the fact that the problem intrusted to him was complex, involving many factors other than those directly connected with mining, and recognized that the beneficial use of these rivers, now overburdened with debris, must be ef- fected by cooperative endeavor on the part of several interests. The public interests in agricultural reclamation, as well as in placer mining, must now be harmonized with the public inter aSt in nauioofior, Tn s4- ,o,..I,.-sz-.--