Metadata: Identification_Information: Citation: Citation_Information: Originator: C.M. Wentworth Publication_Date: 2015 Title: Physical Subdivision and Description of the Water-Bearing Sediments of the Santa Clara Valley, California Edition: 1.0 Geospatial_Data_Presentation_Form: ArcInfo grid Series_Name: U.S. Geological Survey Scientific Investigations Report Issue_Identification: SIR 2015-5017 Publication_Information: Publication_Place: Menlo Park, CA Publisher: U.S. Geological Survey Other_Citation_Details: Online_Linkage: http://pubs.er.usgs.gov/publication/sir20155017/ Description: Abstract: This set of elevation surfaces in the Santa Clara sedimentary basin extends from a simplified version of the ground surface down through the basal surfaces of eight cyclic sedimentary sequences to the buried bedrock surface beneath the Quaternary section. For each of the eight cycles, an internal boundary is also defined between an upper fine-grained interval and a lower coarse-grained interval. The surfaces are based on depths defined in control wells and other points (topography, seismic reflection and refraction points, depending on the particular boundary), which were gridded using the ArcInfo function TOPOGRID (see text for discussion). Those parts of each grid outside its area of control (see digital point maps wells, wells1, and bdrk, and plates 1 and 2) have no validity. Some surfaces have been modified slightly in areas of poor control to prevent their intersection with vertically adjacent surfaces (see Process Description, below). All values are elevations relative to sea level in feet. Raster cell size is 100 m. Purpose: These data served as the basis for the surface grids and contours shown in plates 1 and 2, and can be used to represent those surfaces in other digital applications (always recognizing their limitations, particularly outside areas of control). They can also be used to prepare vector contours and thickness grids (differences between selected grids). Supplemental_Information: Specific processing steps and logic are discussed in the text of this report and are listed by surface below under Process Description. All digital work was done using workstation ArcInfo, version 9.3 (and earlier), with version 3.5 of the menu interface ALACARTE (Fitzgibbon and Wentworth, 1991; Fitzgibbon, 1991; Wentworth and Fitzgibbon, 1991). The raster grids were generated as ArcInfo grids and are presented here in that form. The projection used is UTM, zone 10, NAD27, Clarke 1866 spheroid, with X,Y dimensions in meters. Elevations are in feet relative to sea level. Reviews_Applied_to_Data: The report of which this file is a part was scientifically reviewed, including elevation contours derived from raster grids of the surfaces defined herein. Related_Spatial_and_Tabular_Data_Sets: Many other digital maps and raster grids accompany this report (see Appendix E). Other_References_Cited: Fitzgibbon, T.T., 1991, ALACARTE installation and system manual (version 1.0): U.S. Geological Survey, Open-File Report 91-587B. Fitzgibbon, T.T., and Wentworth, C.M., 1991, ALACARTE user interface - AML code and demonstration maps (version 1.0): U.S. Geological Survey, Open-File Report 91-587A. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2015 Currentness_Reference: The date given is the publication date. The information in the report is the most up-to-date available at the time of publication. Status: Progress: Complete Maintenance_and_Update_Frequency: As needed Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -122.182 East_Bounding_Coordinate: -121.718 North_Bounding_Coordinate: 37.582 South_Bounding_Coordinate: 37.209 Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: Quaternary geology Theme_Keyword: surficial geology Theme_Keyword: Santa Clara Valley Theme_Keyword: Santa Clara basin Theme_Keyword: elevation surfaces Theme_Keyword: structural surfaces Theme_Keyword: cycle elevations Theme_Keyword: alluvium Theme_Keyword: bedrock surface Place: Place_Keyword_Thesaurus: None Place_Keyword: United States of America Place_Keyword: California Place_Keyword: Santa Clara County Place_Keyword: San Mateo County Place_Keyword: Alameda County Stratum: Stratum_Keyword_Thesaurus: None Stratum_Keyword: cycle Stratum_Keyword: bedrock surface Temporal: Temporal_Keyword_Thesaurus: None Temporal_Keyword: Quaternary Temporal_Keyword: Pleistocene Access_Constraints: None Use_Constraints: Uses of these digital raster grids should not violate the spatial resolution of the data. The grids are based on wells and other control points the locations of which come from sources that do not specify location accuracies, making the locations used here only approximate. Raster cell size is 100 m, which limits the areal specificity of the grid values. Values outside the area of original control (see plates 1 and 2 and digital maps wells and wells1) have no validity at all, and may be highly misleading. Plotting at scales larger than about 1:250,000 will not yield greater real detail, nor will extraction of XY locations from the map yield highly accurate locations. The actual uncertainty is unknown, although for most of the original control points it is probably less than 100-200 m. Where this database is used in combination with other data of higher resolution, the resolution of the combined output will be limited by the lower resolution of these data. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: USGS Geology, Minerals, Energy and Geophysics Science Center Contact_Person: C. M. Wentworth Contact_Address: Address_Type: mailing address Address: 345 Middlefield Road, MS 973 City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: USA Data_Set_Credit: The digital raster grids were prepared by C.M. Wentworth as described above (see Description). Security_Information: Security_Classification_System: None Security_Classification: Unclassified Security_Handling_Description: None Native_Data_Set_Environment: Windows, Arc-Info version 9.3 (and earlier) Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Not applicable for raster data. Logical_Consistency_Report: Unspecified Completeness_Report: Complete Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Horizontal_Positional_Accuracy_Report: Uncertainty estimated to be as much as 100 or more meters, at least locally, due to uncertainty in the location of the control points on which the grid is based. The raster cell size of 100 m represents a similar resolution. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: Vertical_Positional_Accuracy_Report: Elevations at control points are probably good to 1 foot or so. Elsewhere accuracy is difficult to estimate, but increases with distance from control points and can become extreme beyond the outer limits of control, where the grid values become meaningless. Lineage: Process_Description: Control for each surface was assembled in ArcInfo in a vector point layer (coverage) and consisted of elevations (in feet) at wells, selected points on the topographic surface, and seismic reflection and refraction profiles, as discussed in the text and described in metadata files for the relevant digital point maps (wells-metadata.txt, wells1-metadata.txt, and bdrk-metadata.txt). Those point elevation values were then gridded using the ArcInfo function TOPOGRID (see text for discussion). Inasmuch as each of the cycle boundaries was once a topographic surface, the resulting gridded surfaces were inspected for local distortions not consistent with such a history. Those few points that caused such distortions were rejected and the surfaces regenerated. Few points were rejected (see table C1 in text) and all of the rejected points were represented by drillerÕs logs. A further test was that none of the surfaces should intersect vertically adjacent surfaces, and where that occurred, fixes were applied either by adding elevation points (mostly at wells where no elevation had been defined) or by forcing equivalence to or specific distance from that adjacent surface (using grid functions). Such adjustments were particularly important for the closely spaced surfaces C0, C1b, and C1. Specifics for each of the surfaces are listed below under the grid names. And see plates 1 and 2 for graphic representations. el-C0: Generalized topographic surface Ð An array of elevations at 500 m spacing was sampled from an elevation grid of the region (see text for discussion) and that array then gridded using TOPOGRID. C1b: Internal top/bottom boundary within cycle 1 Ð Control from wells (wells1) was gridded with TOPOGRID, then forced areas where C1b intersected C1 to equal C1 (that is, to define areas where there is then no lower coarse interval). Because cycle 1 does not everywhere extend to the edge of the basin, an outer vector boundary (see digital point layer wells1 and associated metadata file) was employed during the gridding. el-C1: Base of cycle 1 Ð Well and topographic control on exposed cycle 2 deposits was gridded with TOPOGRID and then, where the surface rose above C0, it was forced to lie 1 foot below that surface. el-C2a: Base of upper coarse interval in cycle 2 Ð Well control was gridded with TOPOGRID, and then regridded after rejecting 5 control points. el-C2b: Internal top/bottom boundary within cycle 2 Ð Well control was gridded with TOPOGRID, with no further adjustment needed. el-C2: Base of cycle 2 Ð Well control was gridded with TOPOGRID, and the surface regridded after rejecting 3 control points and adding 2 constructed points to limit artifacts in the surface. el-C3b: Internal top/bottom boundary within cycle 3 Ð Well control was gridded with TOPOGRID, with no further adjustment needed. el-C3: Base of cycle 3 Ð Well control was gridded with TOPOGRID, and after rejecting 6 control points was regridded. el-C4b: Internal top/bottom boundary within cycle 4 Ð Well control was gridded with TOPOGRID and, after adding 1 constructed point (at well 587), regridded. el-C4: Base of cycle 4 Ð Well control was gridded with TOPOGRID and, after rejecting 3 control points, was regridded. el-C5b: Internal top/bottom boundary within cycle 5 Ð Well control was gridded with TOPOGRID and, after constructing control at well 942 and midway between wells 930, 935, and STPK to constrain a large bulge in the surface, regridded. el-C5: Base of cycle 5 Ð Well control was gridded with TOPOGRID and, after rejecting 8 points, was regridded. el-C6b: Internal top/bottom boundary within cycle 6 Ð Well control was gridded with TOPOGRID. A vector boundary was used to limit the eastern extent of the grid, beyond which there is no control. el-C6: Base of cycle 6 Ð Well control was gridded with TOPOGRID and, after rejecting 4 control points, was regridded. A vector boundary was used to limit the eastern extent of the grid, beyond which there is no control. el-C7b: Internal top/bottom boundary within cycle 7 Ð Well control was gridded with TOPOGRID, with no further adjustment needed. A vector boundary was used to limit the eastern extent of the grid, beyond which there is no control. el-C7: Base of cycle 7 Ð Well control was gridded with TOPOGRID and, after rejecting 1 control pint, was regridded. A vector boundary was used to limit the eastern extent of the grid, beyond which there is no control. el-C8b: Internal top/bottom boundary within cycle 8 Ð Well control was gridded with TOPOGRID and, after constructing control at well 789, regridded. A vector boundary was used to limit the eastern extent of the grid, beyond which there is no control. el-C8: Base of cycle 8 Ð Well control was gridded with TOPOGRID. A vector boundary was used to limit the eastern extent of the grid, beyond which there is no control. bdrk: Surface of underlying bedrock surface Ð Well and other control was gridded with TOPOGRID. The other control consisted of seismic reflection and refraction points and surface elevations along bedrock contacts. Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Raster Raster_Object_Information: Raster_Object_Type: Grid Cell Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: 1.0 Ordinate_Resolution: 1.0 Planar_Distance_Units: METERS Geodetic_Model: Horizontal_Datum_Name: NAD27 Ellipsoid_Name: Clarke 1866 Semi-major_Axis: 6378206.4 Denominator_of_Flattening_Ratio: 294.98 Xshift: 0.0000000000 Yshift: 0.0000000000 longitude of central meridian: -123 latitude of projection's origin: 0.000 Entity_and_Attribute_Information: Overview_Description: Entity_and_Attribute_Overview: The grids are original to this report, and were generated with a cell size of 100 m in floating point format. Entity_and_Attribute_Detail_Citation: This metadata report. Distribution_Information: Distributor: U.S. Geological Survey Contact_Information: Digital Form Contact_Person_Primary: Contact_Person: C.M. Wentworth Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: 345 Middlefield Rd., M/S 973 City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: USA Contact_Instructions: Please contact by mail or website. Resource_Description: This digital map is one of numerous vector and raster maps included with the report. Distribution_Liability: Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this publication has been subjected to careful review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. It is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. Standard_Order_Process Digital_Form: Digital_Transfer_Information: Format_Name: Digital Database package, [name to be determined] Format_Version_Number: 1.0 Format_Version_Date: 2015 Format_Specification: Arc-Info v. 9.3 Format_Information_Content: , and accompanying metadata file (this file). File_Decompression_Technique: Transfer_Size: XX MB Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: Fees: No fees for digital forms of the report. Ordering_Instructions: Digital files can be obtained on-line as described above at the publication web-site