L I B R A R Y 



UNIVERSITY OF 



v CALIFORNIA. 



x jy 



PART I. 



GEOLOGICAL MAPPING. 



CHAPTER I. 



MAPPING AND INSTRUMENTS. 



Maps Contour Maps Compass and Protractor Hammer, Pick, 

 Spud, &c. Scales Tracing Boundaries General Propositions. 



Maps. In tracing and mapping geological boundary 

 lines, it is very essential to have as good as possible a 

 map of the district to be surveyed. One that is not 

 tinted and not closely covered with the names of places, 

 for the fewer these are in reason the better but on 

 which such prominent objects as churches, windmills, 

 and so on are shewn with fair typographical accuracy. 

 The physical features should be rendered as distinct as 

 may be, by the insertion of all rivers, brooks, and water- 

 courses ; and if there be hill-shading, drawn with even 

 an approach to accuracy, it will be an improvement; and 

 heights above the sea-level given in figures here and 

 there are a great advantage. Maps drawn to a scale of 

 one inch to a mile will generally be found the best for the 

 purpose ; they are sufficiently large to admit of the main 

 features being correctly shewn, and a sheet representing 

 many square miles can be carried and referred to without 

 inconvenience. If great accuracy be required as in the 



