The area of the Hamaker, Worden and Lost River quadrangles geologic map lies east of the High Cascades at the south end of Upper Klamath Lake, Oregon. Map coverage includes all of the three named quadrangles, and abuts the Califrnia-Oregon border along the south edge. Situated in the extreme northwestern part of the Basin and Range province, the area is dominated by the horst and graben topography resulting from the extensional tectonics that characterize the Basin and Range of southeast Oregon. The quadrangles span the tectonic graben and topographic basin historically occupied by Lower Klamath Lake, now drained and farmed. The lake basin is bounded on the west by Hamaker Mountain, and on the east by the Klamath Hills and Stukel Mountain. The northwest-trending normal faults that bound Upper Klamath Lake and form the Klamath graben expose up to 600 m of volcanic and sedimentary rocks, ranging in age from late Miocene to Holocene. Surficial deposits of lake and river sediment cover half of the map area. The dominant structures in the quadrangles are N. 30°-40° W.-striking normal faults that rotate fault blocks northeastward on the northeast side of the area and southwestward on the southwest side. Rock in the area is chiefly ~2-7 Ma dark gray lava (basalt and basaltic andesite), pelagonitic basalt and basaltic andesite tuff and contemporaneous to younger cream-colored diatomaceous mudstone. Local outcrops of sandstone and conglomerate cap a few low hills. Rocks in the area are the product of complex interaction between sedimentation, water and volcanism. Basin and Range extension continues to pull the area apart, dropping basins lower relative to ridges while sedimentation, helped along by periodic ash fall from the High Cascades, fills basins.
The digital geologic map for the quadrangles have been created as a general-purpose data set that is applicable to land-related investigations in the earth and biological sciences. The map has been generated to further our understanding of bedrock and surficial processes at work in the region and to document evidence for seismotectonic activity in Oregon. The map is designed to serve as a base layer suitable for ecosystem and mineral resource assessment and for building a hydrogeologic framework for the basin(s) in which it occurs. It is not suitable for site-specific geologic evaluations.
publication date
User should use caution when overlaying other data sets and should not make legally binding decisions from this data. These data are subject to change. Acknowledgment of the Oregon Department of Geology and Mineral Industries (DOGAMI) would be appreciated in products derived from these data. Any person using the information presented here should fully understand the data collection and compilation process before beginning their analysis/use. The burden of determining fitness for use lies with the user. To avoid the risk of misinterpretation, invalid results, and erroneous conclusions, the users must consider the original map scale, collection methodology, currency of data, and any other conditions specific to every data element and each dataset as a whole. Potential users are advised to consult with DOGAMI 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. Data collected and interpreted at a scale of 1:24,000. Many lines and polygon boundaries inferred, accompanying traverse map and point data set (if provided) show where direct observations were made, areas without direct observations were completed with geologic inference and airphoto interpretation. Location error for observed features points, lines, and polygons have a +/- 12 m uncertainity and even more for areas covered and not exposed.
800 NE Oregon St, Suite 965
The accuracy of the attributes is unknown
Spatial data is presented in the form of points characterizing the geology only in the quadrangles. This dataset does not have topology. The geology was delineated by the geologist on a 1:24,000, 7.5-minute USGS topographic quadrangle. Check plots of the map were reviewed by the mapper and cartographer for consistency with basic geologic principles and general conformity to USGS mapping standards. This data is not field-checked and is an interpretation of the mapper. No guarantees are provided as to its accuracy.
The mapping project as originally designed has been completed for the quadrangles. The geology of the quadrangles is based on relationships gathered from outcrops, float, and rock exposure on foot or vehicle traverses. Portions of the quadrangle may not have been visited or field checked. Interpretation of the geology in the quadrangles was supplemented by examination of the land surface using digital orthophoto quadrangles with 1 m resolution, overlaid with digital line graphs of contour lines and hydrography, and printed out at 1:600 or 1:12,000 scale. Unit properties are described in the text explanation. All geospatial database elements are attributed.
The data cannot be more accurate than the USGS topographic quadrangle from which it was developed. Positional accuracy of geologic contacts vary based on the techniques and quality of mapping. Still the horizontal accuracy of the coverage should be regarded as unknown.
Field mapping and aerial photograph interpretation; iterative process. Transfer of geologic linework and point data from field maps and aerial photographs to a scale-stable cartographic base of quadrangles Description of Map Units and Correlation of Map Units Polygons, lines, and points representing geologic features and data points were hand digitized from author-prepared base-stable geologic map at 1:24,000 scale. The resultant coverages were attributed with data describing the geologic units, contacts, structures and point locations.
Metadata imported.
Internal feature number.
ESRI
Feature geometry.
ESRI
Unique number assigned to each fault serially
Designates how well the fault is located and whether it is concealed beneath surficial deposits, dictates lines styles on map
Fault was positively identified from field data, plots as solid line with ticks on downthrown side of fault
Oregon Department of Geology and Mineral Industries
Fault was not positively identified, its presence is inferred from other geologic relationships, plots as long dashed line with ticks on downthrown side
Oregon Department of Geology and Mineral Industries
Fault is inferred, but is buried beneath surficial deposits and so does not intersect the ground surface, plots as dotted line with ticks on downthrown side
Oregon Department of Geology and Mineral Industries
Geologic age of youngest units cut by fault
800 Oregon Street #5
No warranty, expressed or implied is made regarding the accuracy or utility of the data described and/or contained herein, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data. It is strongly recommended that careful attention be paid to the contents of the metadata file associated with these data. The Oregon Department of Geology and Mineral Industries shall not be held liable for improper or incorrect use of these data. This information may be updated without notification.
Ordering capability is available through Nature of the Northwest Information Center, 800 NE Oregon Street #5, Portland, Oregon 97232, (503) 872-2750 and a publication list is viewable at: http:/www.naturenw.org
Files for ArcGIS Desktop
Ordering capability is available through Nature of the Northwest Information Center, 800 NE Oregon Street #5, Portland, Oregon 97232, (503) 872-2750 and a publication list is viewable at: http:/www.naturenw.org
Contact The Nature of the Northwest Information Center by e-mail, phone, or letter explaining what products are needed.
800 NE Oregon St Suite 965