286 



GRAVITATIONAL METHODS 



[Chap. 7 



Eottfoi Unit's 



in down-throw direction (Fig. 7-117). The Pentland fault near Porto- 

 bello in the Edinburgh district was investigated by McLintock and Phem- 

 ister (Fig. 7-118). This overthrust fault dips toward the west and 

 separates a series of volcanic beds of 500 feet thickness and of east dip 

 from the oil shale group of sedimentaries in the east; hence, a westward 

 tendency of gradients is produced. A satisfactory agreement of theo- 

 retical and experimental 

 values was obtained by 

 assuming a block with in- 

 clined face, 0.42 difference 

 in density, beginning at a 

 depth of 100 feet, and hav- 

 ing a superimposed syncline 

 west of the fault in the lava 

 beds. 



At Dossor (see Numerov, 

 footnote 134) S. Mironov 

 investigated a fault on the 

 west side of the field, 

 separating the Senonian 

 from (productive) Jurassic 

 beds overlying Permo-Tri- 

 assic and salt formations.^" 

 Matuyama and Higasin- 

 aka determined the tor- 

 sion balance anomalies of 

 a fault of 70 meters dis- 

 placement in the Takumati 

 oil field, and Vajk^"^ dis- 

 cussed a survey in South 

 America where a maximum 

 in the gradients and curva- 

 tures could be explained 

 by either an anticline or a 

 normal fault. 

 3. Applications in mining. Although Eotvos made some experiments 

 with the torsion balance and magnetic instruments on igneous dikes, it is 



JOO 



rooo 



Fig. 7-118. Torsion balance results on Pentland 

 fault (after McLintock and Phemister). 



186 \Y p p McLintock and James Phemister, Great Britain, Geol. Survey, Summ. 

 of Progr., pt. II, 10-28 (1928). 



1" S. Mironov, Geol. Comm. Vestnic, No. 5 (Leningrad, 1925). 



"8 M. Matuyama and H. Higasinaka, Japan. J. Astron. and Geophys., VII(2), 

 47-81 (1930). 



"9 R. Vajk, World Petrol. Congr. Proc. B I, 140-142 (London, 1933). 



