1194 



EXPLORATION GEOPHYSICS 



Self-Potential logging (continued) 



S.P. log, 1037 



field example, 1040-1048 

 recording of, 1048 



S.P. peaks, shape and amplitude, 1042-1048 



well conditions effecting log, 1043, 1044 

 Shale: 



density of, 126 



magnetic susceptibility of, 165 



radioactivity intensity range, 1102 



spontaneous potential of, 1044, 1045, 1051 



velocity of, 660 

 Sheave wheel, logging, 1056, 1069 

 Shipborne magnetometer, 244 



Shooting {see Explosives, Seismic drilling equip- 

 ment. Velocity shooting. Water shooting and 

 Air shooting) 

 Shot hole, 661, 666 

 Shoran navigational system, 908, 909 

 Side-wall sampling, 1083-1087 



correlation with electrical logging, 1086 



efficiency, 1086, 1087 



field operation, 1086 



mechanical samplers, 1083, 1084 



percussion or gun samplers, 1084, 1085 



rotary method of coring, 1083 



the cores, 1086 

 Sine galvanometer, 94 

 Slim-hole drilling, 16, 21 



cost of, 37 



technique of, 21 

 Smooth contour mapping method, 420, 421 

 Snell's law, 664, 665 

 Soil analysis, 17, 943 



costs, 955 



for non-volatile constituents, 951 

 fluorographic method, 953 

 surveys, 953, 954 



for volatile hydrocarbons, 943, 944 

 analytical technique, 944, 948 

 results of surveys, 948-951 

 sampling, 944 

 Soil dynamics {see Seismic investigation of) 

 Solenoid instrument, 179 

 Sonde: 



lateral, 1025-1027 



multi-electrode, 1025 



normal, 1024, 1025 

 Sonic-wave method {see Pressure-wave method) 

 Sonograph method, 825-835 

 Spontaneous Polarization methods {see Self- 

 potential electrical method) 

 Spot correlation (seismic), 704, 705 

 Static gravimeter, 371 

 Static S.P. diagram, 1041, 1042 

 Stratigraphic traps, 33 

 String type galvanometer, 814, 815 

 Structural traps, 33 

 Subsurface pressure determinations, 1130, 1133, 



1134 

 Supply wells, 1141 

 Surface wave, 651, 667 

 Surveying (radio) techniques, 905-911 



Susceptibility {see Magnetic susceptibility) 

 Swedish mining compass, 112 

 Synclines, 267, 286 



Tagg's (electrical) method, 491-496 

 Taylor mechanical seismometer, 807 

 Telluric current, 455 

 Temperature (thermal methods) : 



and porosity, 973, 974 



and moisture, 973, 974 



anomalies, 976, 977 



areal variations, 974, 982 



depth curve, 973, 974 



diurnal variations, 978 



measurements in bore holes {see Borehole 

 temperature measurements) 



near surface variations, 982 



periodic variations, 979 



rate of change, 968-971 



vertical changes, 971, 975 

 Terrain computations, gravity, 337-339 

 Terrain correction, gravity: 



computations, 337-340 



for torsion balance, 331-339 



tables for gravity, 406, 407 



zone chart method, 404-409 

 Terrestrial photogrammetric mapping, 392-398 



construction detail, 395, 396 



fundamental theory, 393, 394 



instrumentation for reading data, 396, 397 



operation procedure, 397 

 Thalen-Tiberg magnetometer, 113 

 Thermal: 



age of the earth, 985 



conductivity constants in C.G.S. units, 985, 

 986 



field operations, 922, 984 



field technique, 984-986 



gradients, 973, 974, 1063 



heat flow, theory of {see Heat flow), 967-971 



patents, 986 



sources, internal, 982 

 Thermal equilibrium, 1064-1065 

 Thermal surveys: 



areal studies, 974-978 



by porosity and temperature, 973, 974 



by vertical thermal gradients, 971, 972, 975 



field operations, 983-985 

 Thermometer, 1064 

 Thermometric method, 1074 

 Thorium, 991, 992 

 Thyssen, 376, 377 

 Torsion balance, 291-367 



Cavendish, 250 



comparison with gravimeter, 368, 369 



computation of data, 328-360 



double beam, 323 



Eotvos-Askania, 298-304 



field procedure, 326, 336, 337 



fundamental equations of, 321, 322, 323 



interpretation and plotting of results, 340-360 



observation of beam deflection, 319 



