4 CONTENTS. 



History and legal basis for land classification — Continued. 

 Agencies and methods of classification — Continued. 



Classification by the Geological Survey — Continued. Page. 



Water-power sites 41 



Reservoir sites 42 



Public water reserves 42 



Withdrawal acts 43 



Separation acts 45 



Desirable new legislation 46 



Classification of mineral lands 50 



Field methods 50 



Development 50 



Detailed survey 53 



Methods used when a topographic base is available 53 



Methods used when a base map must be prepared 54 



Methods followed when the Land Oflice survey affords a 



base map 58 



Reconnaissance survey 60 



Public-land surveys., 61 



Preparation of data for classification 63 



Coal lands 65 



Purpose of classification 65 



Methods of classification 66 



Principles involved 66 



Factors involved 67 



Essentials of workability 67 



Quality 68 



Thickness 69 



Depth 73 



Classification by 40-acre tracts or lots 78 



Outcrop coal and burned coal 78 



Methods of valuation 79 



Cost of coal in the ground 79 



Factors involved! 81 



Effect of quality on price 82 



Effect of mining cost on price 82 



Value of thin coals 83 



Value of irregular beds 87 



Value per acre 90 



Reduction for depth 91 



Allowance, for faults 93 



Effect of intrusions 94 



Allowance for other factors 94 



Reduction for distance from railroad 95 



Maximum price 95 



Review of classification 95 



Regulations for the classification and valuation of public coal 



lands :. 9g 



Restoration , 97 



Field work on coal lands gg 



General nature of the work 98 



Location gg 



Stratigraphy gg 



Extent and thickness of coal beds 100 



