1066 



Subsurface Geologic Methods 



layer for the Bouguer effect would be in error, separate corrections are 

 applied to gravity data. 



Geologists examining gravity-meter maps should be aware of the 

 importance of the elevation-correction factor and the need for terrain 



Figure 561. Modern portable gravity 

 meter enclosed in thermos bottle for 

 thermal insulation. Weight of meter 

 is six pounds. (Reproduced permis- 

 sion Houston Technical Laboratory. 



corrections in certain areas. In many areas, particularly those of rugged 

 terrain, the use of the proper elevation factor and terrain corrections 

 make data easier to interpret. Wrong factors cause the final map to 

 appear ragged and may cause "false" anomalies to appear on topographic 

 features. 



Anomalies occurring on "hanging" or "stub" lines, which have not 

 been rerun by the surveyor and the meter operator, should be eliminated 

 from consideration unless detailed work in the area substantiates the 

 "hanging" line. Many "anomalies" found to lie on these unchecked lines 

 disappear with additional work. 



