10 CLASSIFICATIOK OF THE PUBLIC LANDS. 



efficiently assisted by C. E. Lesher, who is independently responsible 

 for the short section on " The preparation of data for classification." 

 Mr. Lesher should be credited with many of the office methods which 

 facilitate the prompt and accurate handling of data contributed by 

 the field men of the Survey. 



Field methods are discussed by E. G. "Woodruff, C. H. Wegemann, 

 E. W. Richards, and F. R. Clark, all of whom are members of the 

 geologic branch and have had wide experience in field work leading 

 up to land classification. Under the topic " Oil and gas lands," J. D. 

 Northrop, who has had experience in the California oil fields, and 

 C. H. Wegemann, a geologist of broad experience in the Rocky 

 Mountain fields, have collaborated in the discussion of the geologic 

 occurrence of oil and gas, while Mr. Northrop has contributed the 

 section on classification. In a similar way, under " Phosphate lands," 

 A. R. Schultz and R. W. Richards, the former the chairman of the 

 phosphate section in the land-classification board and the latter a 

 geologist who has worked out with great thoroughness and detail 

 the complicated structural problems of the phosphate fields in south- 

 eastern Idaho and adjacent parts of Wyoming, have collaborated in 

 the general discussion of phosphate problems, Mr. Schultz being re- 

 sponsible for the section on classification. The description of potash- 

 bearing lands and their classification is the joint contribution of A. R. 

 Schultz and H. S. Gale, Mr. Gale being the geologist in charge of 

 the section of nonmetalliferous deposits of the geologic branch. E. H. 

 Finch, of the land-classification board, who has been closely identi- 

 fied with the cooperative work between the Sui^ey and the General 

 Land Office, has contributed the section on " Miscellaneous nonmetal- 

 liferous lands," and F. C. Calkins, one of the experienced economic- 

 geologists of the Survey, who has had much to do with the classifi- 

 cation of the lands in the Northern Pacific grant, has written the 

 discussion of metalliferous mineral lands and the problems involved 

 in their classification. The section on " By-products of mineral-land 

 classification " was written by G. S. Rogers, a geologist of the geo- 

 logic branch, whose recent work has been done in the western coal 

 fields. 



The discussion of classification in relation to water resources has 

 been prepared under the direction of N. C. Grover, chief engineer 

 of the land-classification board, M. O. Leighton, Herman Stabler, 

 E. C. La Rue, and W. B. Heroy collaborating. Messrs. Grover, 

 Stabler, and Heroy have prepared the sections relating to classifica- 

 tion and office procedure, while Mr. Leighton, as chief of the water- 

 resources branch of the Survey, and Mr. La Rue, one of the ex- 

 perienced field engineers of that branch, have cooperated in prepar- 

 ing the discussion of field methods. 



