Chap. 7] 



GRAVITATIONAL METHODS 



279 



feet, is indicated by a maximum, surrounded by a minimum, due to the 

 increase in section with depth. Results of fan shooting across this dome 

 are illustrated in Fig. 9-38. Fannet shows a typical maximum but no 

 minimum, and it is assumed to be a dome of nearly vertical sides. The 

 pattern of gradients and curvatures is quite regular; depth to the top of 

 the cap is about 900 feet. Clark and Eby"^ have also illustrated the mag- 



Dome; grawify mmimum 

 Cy Oil show 



TT^ Gradient ofgra¥ity 



Jskine. 



wautschiunas 



Fig. 7-109. Gravity anomalies between Dossor and Iskin, Emba district, Russia 



(after Numerov). 



netic results for this dome (negative anomaly of about 20 to 25 gammas). 

 The Sugarland dome, for which the torsion balance results have been 

 published by the same authors, is an example of a dome of moderate depth, 

 which shows a large minimum and a small maximum. The top of the 

 cap is at a depth of about 3500 feet; salt was encountered at a depth of 

 4280 feet. 



Ibid. 



