239 



bench marks farther out, checking and rechecking the points to be used 

 as bench marks. Continue this until bench marks have been established 

 over area to be detailed. Plot curve and make corrections for eleva- 

 tions of points to be used for bench marks. After the bench marks 

 have been established the method of procedure is same as in Method No. 

 2 in all respects. 



This method is very good and quite accurate for obtaining quick 

 results. 



Method No. 5. 



The fifth method is simply reconnaissance work, or scouting, as 

 it is frequently called. 



With this method the geologist drives over the country observing 

 the dip of the i^ock strata by use of the hand level, aneroid barometer 

 or eye. 



Wherever an exposure of rock is observed the hand level is used to 

 determine the approximate amount of dip in any distance. The direc- 

 tion of dip may be obtained by use of the compass. The geologist must 

 always know the height of his eye from the ground. 



Example: Suppose strata is dipping west and in a distance of 

 one-quarter mile the geologist finds the dip to be five times the height 

 of his eye which is 5 feet 6 inches, therefore the rock would be dipping 

 27 feet 6 inches in one quarter mile, etc. 



The aneroid barometer may be used in scouting to determine ap- 

 proximate amount of dip for short distances. Read elevation of outcrop, 

 then follow strata for distance exposed, with occasional readings, noting 

 amount of variation from first reading. This gives the amount of dip. 



Example: If aneroid reads 700 feet at a given point and outcrop 

 is followed east one-quarter mile and then reads 670 feet, showing 

 strata dips east 30 feet in one quarter mile. Supposing second reading 

 was 732 feet then strata dips west 32 feet in one quarter mile, etc. 



An experienced geologist should be assigned to scouting work. The 

 greatest value of this method is that it permits a large territory to be 

 covered rapidly and a great part eliminated. An experienced man will 

 be able to find most of the structure. Later, if deemed advisable, the 

 various structures reported by the scout can be worked in detail by 

 either of the first two methods. 



