884 MISCELLANEOUS GEOPHYSICAL METHODS [Chap. 12 



made by taking and testing samples, by open-bottom chambers, by ema- 

 nometers, and by Geiger-Mueller counters. 



Results of radioactivity tests of oil well samples have been published and 

 discussed by Ambronn. ^ In one of these, an increase of activity (alpha 

 radiation) immediately below an oil sand was noted. Because of the high 

 absorbing power of oil for radon, a peak of alpha-ray activity should be 

 expected to coincide with the sand. As stated in Chapter 11,^^ there is 

 no noticeable increase in gamma radiation in oil sands. Underground 

 observations of radioactivity for locating pitchblende seams have been re- 

 ported by von dem Borne and B^hounek. At a distance of 6 meters 

 from a pitchblende seam, the latter observed an activity of 200 M.U. (per 

 liter air, taken from drill holes) while at 17 meters distance the activity 

 had dropped to about 3 M.U., and at 29 meters to about 2 M.U. It is 

 likely that measurements have been made at the surface for the same 

 purpose in the more recently discovered radium districts of the Belgian 

 Congo and in Canada, although definite reports have not been published. 

 In balneological work, the activity of spring waters is tested in routine 

 fashion. The rather extensive literature on the subject has been reviewed 

 by Ambronn.^^ Location of oil by surface measurement of the penetrating 

 radiation appears possible only on shallow deposits, according to Bogoiav- 

 lensky and Lomakin, who published the results of some experimental pro- 

 files across the Maikop field in Russia.^ Above these shallow deposits, 

 the radiation increased only 1 or 2 ions, the error being of the order of 

 0.2 ions. 



Radioactivity measurements seem best adapted to the location of faults, 

 fissures, contacts, and some types of mineral veins. An increased activity 

 (alpha radiation) was first observed by Ambronn on some faults near 

 Blankenburg and above an iron ore vein near Ilfeld in the Harz Moun- 

 tains." Similar observations on fracture zones in the Black Forest (near 

 Wildbad) were reported by Link and Schober.^* Mueller^^ verified these 

 results on mineralized veins and contact zones in the Siegerland. Some 

 of his results are reproduced in Fig. 12-7. Patriciu surveyed a number 

 of profiles across the Leine graben near Goettingen and located some 

 hitherto unknown fault zones through an alluvial cover of 20 or 30 feet."^ 



" Elements of Geophysics, p. 125, McGraw-Hill (1928). 

 " P. 864 



^' Habilitationsschrift (Breslau, 1905). 

 " Loc. cii. 



" Elements of Geophysics, p. 131. 

 " Op. cit., see p. 881. 

 " Jahrb. Hall. Verb, 3(2), 21 (1921). 

 28 Gas und Wasserfach, 69, 225-28 (1926). 

 "F. Mueller, Zeit. Geophys., 3(7), 330-36 (1927). 



30 Preuss. Geol. L-A. N. F., 116 (1930); curves reproduced by J. N. Hummel, 

 Handb. Exper. Phys., 26 (3), 537 (1930). 



