The geologic map was prepared using a variety of data sources, which were digitally integrated with MapInfotm GIS software . The primary sources of data were 330 field observations in natural and man-made exposures. The second major source of data were the logs of over 600 approximately-located water and engineering borings in and adjacent to the quadrangle. Eleven oil and gas stratigraphic or exploratory wells were drilled in the quadrangle in 1925, 1956 and 1957, and logs of these wells were also sources of data.
Cuttings from several wells in the map area were analyzed geochemically and interpreted (USGS, 2006) by Dr. Marvin Beeson and Mr. Terry Tolan. Together with whole rock, major and trace element geochemical analyses of approximately 59 samples of Columbia River Basalt, they were used to help define volcanic units.
To avoid the risk of misinterpretation, invalid results, and erroneous conclusions, the users must consider original map scale, collection methodology, and any other conditions specific to every data element and each dataset as a whole. Potential users are advised to consult with DOGMAI to gain an understanding of the inherent limitations of this data set and its scope of inference. Also, the user must be aware that errors and conditions originating from physical sources involved in developing a dataset may be reflected in the data, and that the digital processing performed during preparation, storage, and transmission of the dataset may have exacerbated such errors and/or introduced additional ones.
The Oregon Department of Geology and Mineral Industries created and maintains the spatial data sets. Credit should always be given to the data source and/or originator when the data is transferred or printed.
In the data set for bedrock units, the entity type is a geologic unit as shown on the Dixie Mountain bedrock map (this publication), while names (Member, Formation and Unit) are described in accompanying report. Each geologic unit consists of an abbrevation beginning with time correlation (but not always) and letters for genetic rock type.
The classification scheme for the field called "Unit" is a simple classification of single units, as follows:
Miocene-Pleistocene Fluvial Sedimentary Rocks Troutdale Formation Ttg = Conglomerate and sandstone unit Neogene Volcanic Rocks and Older Sedimentary Rocks Columbia River Basalt Group Wanapum Basalt Frenchman Springs Member Twfs = Basalt of Sand Hollow Grande Ronde Basalt Member of Sentinel Bluffs Tgsb = Basalt of McCoy Canyon Member of Winter Water Tgww = Basalt of Winter Water Member of Ortley Tgo = Basalt of Ortley Scappoose Formation Ts = Marine sandstone unit
All DOGAMI publications, both in and out of print, are available for inspection at the Department's offices (most reports "on file" are in the Portland office only) and at many state-document depository libraries in Oregon, including most Oregon college and university libraries. Publications are also available via interlibrary loan from the Oregon State Library, State Library Building, Salem, OR 97310.
1. complete explanatory text in PDF format in two file sizes, one suitable for onscreen viewing and one suitable for high-quality printing ( O-08-07_onscreen.pdf and O-08-07_print.pdf).
To view the text: The text file is in Adobe Acrobat portable document format (.pdf). A free Adobe Acrobat Reader can be obtained from Adobe Systems Inc., San Jose, CA. <http://www.adobe.com>.
2. map_sheets folder containing O-08-07Map.pdf: 36 by 60 inch sheet.
3. metadata folder: Metadata is a documentation of the spatial map (GIS) data and is provided in three file formats: .htm, .txt, and .xml.
4. geochemistry folder: DixieMtnSampleChem.xls.
5. gis folder: The digital map files are available in two formats: shp - native file format of ESRI ArcGIS software by ESRI, Redlands, California.
Free viewer software can be downloaded from <http://www.esri.com/software/arcexplorer/index.html> and .tab - native file format of MapInfo GIS software by MapInfo Corporation of Troy, New York. You can download the free ProViewer software from <http://www.mapinfo.com/software/proviewer/index.html>. MapInfo Files Readme: The MapInfo files that were used in the creation of the Preliminary Geologic Map of the Dixie Mountain 7.5' Quadrangle, Columbia, Multnomah and Washington Counties, Oregon: Open-File Report O-08-07 have been included on this CD. All of these MapInfo files are contained within the folder named "tab". ArcGIS Files Readme: An ArcMap file (ERSI) has been included on this CD and contains shapefiles (.shp) of the bedrock and surficial units; contacts (unit boundaries); samples; fold, and faults found on this quadrangle. The shapefiles were created by conversion of the MapInfo files mentioned above. All of these ESRI files are contained within the folder named "shp".