iv NOTE. 



The following Geological Maps, forming a part of those supplementing 

 Volume III, based upon the topographical sheets, have been published, 

 i. e., Title-page, Index Sheet, Restored Outline of Lake Bonneville, Nos. 50, 

 59, J of 58, and £ of 66, 67, 75, 76, and 83. Other sheets are in the course 

 of completion. 



The Topographical Atlas referred to, embracing the entire area west 

 of the 100th meridian, will comprise 95 sheets, on a scale of 1 inch to 8 

 miles, numbered consecutively from 1 to 9r>, inclusive, while the " Geolog- 

 ical Atlas" will consist of the same number, using the topographical maps 

 as a base. (See Progress Map of 1878.) Upon a number of the topo- 

 graphical maps as a base, the classification of lands into the following divis- 

 ions, (1) Agricultural with irrigation, (2) Timber, (3) Grazing, (4) Arid 

 and Barren, is shown by colors. It is intended to expand this classification 

 to embrace the entire area, thus gathering data upon which a new legal 

 subdivision to settlers, to accord with presumable values as to class, may 

 be made, pursuant finally to the following divisions: 



r without irrigation. 



1. Arable or Agricultural, < with irrigation (sufficient water being avail- 



' able) or by drainage. 



Lai'ge, ) with prevailing species, as Live 

 2. Small, > Oak, Cedar, etc. 



1. Good, ) with species and quality of 



2. Bad, ) grasses. 



4. Arid or barren, including "desert lands." 



5. Swamp, tide, and overflowed. 



6. Location of the precious and economic minerals, such as — 



2. Timber, j 



3. Pasturage or Grazing, 



1. Gold, in 



place 



or placer. 



8. Tin and nickel. 



2. Silver. 







9. Antimony and arsenic. 



3. Cinnabar. 





10. Sulphur. 



4. Copper. 







11. Sodium, chloride and carbonate of. 



5. Lead. 







12. Alum and borates. 



6. Iron. 







13. Peats, marls, and clays. 



7. Coal. 







14. Asphaltum, petroleum. 



Each full atlas sheet represents two degrees and forty-five minutes in 



