Gravity map and data used to infer details of the geologic structure of the area. Surveys were conducted during or prior to 1975.
Geophysical information republished in improved formats because the
information was otherwise difficult to obtain. Original study was
conducted in support of the resource appraisal of the Crump Geyser
Known Geothermal Resource Area (KGRA). This area was designated as a
KGRA by the USGS, and this designation became effective on December
24, 1970 (Godwin, and others, 1971). The land classification
standards for a KGRA were established by the Geothermal Steam Act of
1970 (Public Law 91-581). Federal lands so classified required
competitive leasing for the development of geothermal resources.
Currentness_Reference:Original report of 1975 republished in 2006
SDTS_Point_and_Vector_Object_Type:Entity point Point_and_Vector_Object_Count:355
Horizontal_Datum_Name:North American Datum of 1927 Ellipsoid_Name:Clarke 1866 Semi-major_Axis:6378206.4 Denominator_of_Flattening_Ratio:294.98
Attribute_Label:STA_CODE Attribute_Definition:Station identification and characteristics Attribute_Domain_Values:
Values are given in two parts, separated by a space.
The first part is an identifier without substantial scientific significance.
The second part is a coded string of four characters, one upper case letter followed by three decimal digits.
The characters in this coded string are interpreted according to the following tables:
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
Attribute_Label:LATITUDE Attribute_Definition:Geographic latitude Attribute_Domain_Values:
This report is preliminary and has not been reviewed for
conformity with U.S. Geological Survey editorial standards (or
with the North American Stratigraphic Code). Any use of trade,
product, or firm names is for descriptive purposes only and does
not imply endorsement by the U.S. Government.
Format_Name:Shapefile Format_Version_Number:1.0 Format_Information_Content:Principal facts from gravity stations File_Decompression_Technique:unzip