Geophysical studies of the Crump Geyser known geothermal resource area, Oregon, in 1975

 Table 2. Location description code (digit one).
   [The number after the alphabetical code indicates the total number of gravity stations for which the code was used.]
 B  45 On level-line benchmark incorporated into U.S. Geological Survey vertical control system.
 N  14 Near benchmark.
 P 188 Location of surveyed elevation.
 X   5 Near location markers such as section corners.
 D   1 Near assumed location of any of the above markers that were destroyed or not found.
 R   1 Lake or reservoir elevation determined from leveling to benchmark.
 F  32 Near a location with or without a marker at which a surveyed elevation is indicated on a published topographic map.
 G  58 Near a location (on a manuscript map or a published map) at which spot elevations are determined by photogrammetry or near a doubtful F-location.
 W  12 Near edge of lake or canal; interpolated elevation or elevation given for water at unknown height relative to present level.

 Table 3. Accuracy of elevations (digit two).
 [The number after the numerical code indicates the total number of stations for which the code was used. Note that uncertainty of horizontal location tends to reduce the elevation accuracy].
 Code Number Accuracy (feet)
 1 230  0.1 On benchmark; surveyed elevation
 2  10  0.5 Elevation difference hand-leveled to nearby benchmark
 3   7  1   Near benchmark or checked water level
 4   2  2   Near assumed location of benchmark that was not found
 5  70  5   Near location with 10-foot contour interval
 6  36 10   Photogrammetric elevation on map with 20-foot contour interval
 7   1 20   Uncertain location of spot elevation point

 Table 4. Accuracy of horizontal location (digit three).
 [The number after the numerical code indicates the total number of stations for which the code was used.]
 Code Number Accuracy (feet)
 2 252  84 Near section corners and benchmarks; surveyed locations
 3  80 210 Near road intersection, stream crossings, hillcrests
 4  22 420 Road curve; uncertain spot elevation location
 5   2 840 Location depends on odometer measurement or other estimate

 Table 5. Accuracy of observed gravity (digit four).
 [The number after the numerical code indicates the total number of stations for which the code was used. Accuracies are relative to the value at the Adel base station.]
 Code Number Accuracy (mgal)
 2   3 0.02 Reading repeated several times
 3   8 0.05 Repeated reading
 4 345 0.10 Non-repeated reading