project overview
project partners
schedule and funding
progress
    tertiary volcanic and sedimentary stratigraphy
publications
references

Project Overview

The Lower Crooked River Basin project area is near the intersection of the High Cascades, High Lava Plains, and Blue Mountains geomorphic provinces in Central Oregon (Figure 1). The region is dominated by juniper- and sage-covered high desert terrain with pine forested uplands in the Ochoco Mountains to the northeast; topographic relief in the basin ranges from ~4080 ft (1244 m) in the low-lying hills in the northeast corner of the quadrangle to the floor of Prineville Valley at ~2840 ft (866 m) downstream of the city of Prineville. The Lower Crooked River Basin is a traditional ranching and lumber-milling community that is rapidly transforming to a suburban residential population. Population growth and expansion of development into rural lands in the past decade has raised major issues in the Lower Crooked River Basin that include: 1) geologic controls on surface and subsurface water, 2) geologic controls on landslides, and 3) distribution of trace metals and radioactive geochemical anomalies. Integrated geologic mapping (1:24,000 scale), lithologic description, geochemical and petrographic analyses, and subsurface well log data provide the data necessary to erect a stratigraphic framework for the Lower Crooked River Basin and to refine the geologic relations with the eastern margin of the upper Deschutes Basin. This stratigraphic framework will form the foundation for further geologic, geohydrologic, and environmental analysis and mitigation of public issues in the Lower Crooked River Basin.

Figure 1. Location of DOGAMI – Baker City Field office mapping for 2005 and 2006 USGS STATEMAP projects in the Lower Crooked River Basin. 2005 mapping in green shade; 2006 mapping in brown shade. Yellow outline is the extent of the north half of the Lower Crooked watershed. Black lines indicate the Ochoco Creek and Crooked River drainages.

The current mapping effort builds on the regional stratigraphy established by Smith (1986a) and Sherrod and others (2004) in the Deschutes Basin and detailed geologic maps of the Lower Crooked River Basin that are of comparatively recent vintage. The first large scale reconnaissance geologic maps for the area were made by Hodge (1942) and Williams (1957). Later mapping efforts focused on groundwater studies and mercury mineralization (Robinson and Price, 1963; Waters and Vaughn, 1968a, b), enabling Swanson (1969) to produce a more detailed 1:250,000 scale map of the east half the Bend AMS sheet. Subsequent studies included geologic mapping in the Smith Rock area (Robinson and Stensland, 1979; Obermiller, 1987) and at Grizzly Mountain and Hensley Butte (Thormahlen, 1984; Bingert, 1984); investigation of the geology and geothermal potential at Powell Buttes was examined by Weidenhiem (1980) and Brown and others (1980). Cooperative studies during the 1990’s between the U.S. Geological Survey and Oregon Department of Water Resources detailed the geology and groundwater resources of the adjacent upper Deschutes Basin (e.g., Gannett and others, 2001; Lite and Gannett, 2002; Sherrod and Others, 2004).

Project Partners  [top]

• Crook County
• Crooked River Watershed Council
• Ochoco National Forest and Crooked River Grassland

Schedule and Funding  [top]

The current mapping effort was initiated in 2005 with mapping in the core 7.5 minute quadrangles of Powell Buttes, Huston Lake, Prineville, and Ochoco Reservoir that contain the Crooked River and Ochoco Creek drainages (Figure 1). Work is continuing this year, with efforts focused in the Stearns Butte and Eagle Rock 7.5 minute quadrangles adjacent to Prineville Reservoir and the Hensley Butte and Salt Butte 7.5 minute‘ quadrangles on the Ochoco National Forest northeast of Prineville. Mapping is being funded in part by the USGS National Cooperative Geologic Mapping Program (STATEMAP). Detailed mapping in the Lower Crooked River Basin will conclude in May 2007. Individual quadrangle maps are published upon submission to the USGS as DOGAMI Open-File Reports (see 2006 publications below). A peer-reviewed geologic map and comprehensive report on the geology of the Lower Crooked River Basin will follow the conclusion of field mapping. A local workshop and field trip, bringing all Prineville area stakeholders together, will be held in the autumn of 2007..

Progress  [top]

The following section is an abbreviated discussion of the Tertiary volcanic and sedimentary stratigraphy erected by DOGAMI mapping during 2005 and 2006 in the Lower Crooked River Basin. Relevant references and age dates are provided to add regional context to geologic units described in the text. Please see the 2006 Open-file publications for more detailed assessment of the geology of the Prineville area.

Tertiary Volcanic and Sedimentary Stratigraphy  [top]

Tpb	Basalt of Dry River (Pliocene) – Gray, fine-grained, open-textured olivine-phyric basalt flows that form the capping rimrock northwest of Powell Buttes. Sherrod and others (2004) consider the basalt of Dry River to be about the same age as the basalt of Redmond, which has an 40Ar/39Ar whole rock age of 3.56 + 0.30 Ma (Smith, 1986a).
Td	Deschutes Formation (Pliocene and late Miocene) – Plateau-forming olivine-phyric basalt flows and interbedded sedimentary rocks that fill and cap channels incised into middle Miocene strata. Basalt flows are onlapped by loosely consolidated sand and gravel of unknown age. Equivalent to the Deschutes Formation as defined by Farooqui and others (1981) and Smith (1986a). These rocks were principally derived from the Cascades between 7.4 Ma and 4.0 Ma (Smith 1986a). A majority of the Deschutes Formation in the Lower Crooked River Basin is apparently older than 7.05 Ma based on stratigraphic position beneath the Rattlesnake ash-flow tuff in the Crooked River Canyon (Figure 2). Olivine-phyric basalt flows were erupted from volcanic vents in the basin; sedimentary rocks were derived from local sources.
Tmr	Rattlesnake Ash-flow Tuff (late Miocene) – Pumice-crystal-lithic tuff exposed between reversed polarity Deschutes Formation basalt flows in the western wall of Swartz Canyon and in the Crooked River Canyon (Figure 2). Considered equivalent to the Rattlesnake Ash-Flow Tuff of Walker (1979). A late Miocene age is based on 7.05 + 0.1 Ma 40Ar/39Ar age (Streck, 1994).
Tcp	Prineville basalt (middle Miocene) – Black to dark gray plagioclase-phyric and aphyric, basalt and basaltic andesite lava flows exposed from Prineville Reservoir north to Lake Billy Chinook. The basalt flows are equivalent to the Prineville Basalt as defined by Tolan and others (1989) and Hooper and others (1993). Prineville flows in the Lower Crooked River Basin include Bowman Dam, Hi-Si, and Hi- PT chemical types as defined by Hooper and others (1993). A middle Miocene age is based on a radiometric date of 15.7 ± 0.1 Ma (Smith, 1986a) on the basal flow at Pelton Dam in the Deschutes Basin and intertonguing relationships between reversed magnetic polarity Bowman Dam type flows and R2 Grande Ronde Basalt flows north of the Deschutes Basin (Hooper and others, 1993).
Tmos	Volcaniclastic sedimentary rocks (middle to early Miocene? and Oligocene?) – Moderately indurated deposits of brown to tan tuffaceous siltstone, volcaniclastic sandstone, diatomite, cobble conglomerate, and massively bedded white pumice-crystal-lithic tuff. A middle Miocene age for the upper part of the unit is based upon conformable or intertonguing relationships with overlying flows of the Prineville basalt (Figure 3). Although previously considered to be the upper part of the John Day Formation (Swanson, 1969) herein tentatively considered to be correlative to the Simtustus (Smith, 1986b) and Mascall (Merriam, 1901) Formations. The unit is discordant on the upper part John Day Formation, separated by a distinct angular unconformity.
Tj	John Day Formation (Oligocene) – Succession of Rhyolite lava flows, domes and plugs, ash flow tuff, and tuffaceous sedimentary rocks exposed from Prineville Reservoir northwest to Gray Butte. Equivalent to the John Day Formation of Marsh (1875), Merriam (1901), and Robinson and others (1990). Oligocene age is based on stratigraphic relations and radiometric age dates of rhyolite lava flows and domes between ~28 Ma and 25 Ma (Robinson and others, 1990; McClaughry and Ferns, 2006a; McClaughry and Ferns, 2006b; Ferns and McClaughry, 2006b).
Tc	Clarno Formation (Eocene) – Andesite to rhyolite lava flows, intrusions, and tuff exposed in the Ochoco Highlands northeast of Prineville and south of Prineville Reservoir. Volcaniclastic rocks are a minor component of the stratigraphy in the Lower Crooked River Basin. Equivalent to the Clarno Formation of Merriam (1901) and Walker and Robinson (1990).

Figure 2. Stacked succession of Deschutes Formation olivine-phyric basalt flows and the Rattlesnake ash flow tuff exposed in the Crooked River Canyon south of Prineville. The lowest basalt flow is normal polarity; the upper two basalt flows and the Rattlesnake tuff are reverse polarity.

Figure 3. North-dipping section of the Prineville basalt exposed along the O’Neil Highway, northwest of Prineville. The Prineville basalt here conformably overlies shard-rich tuff assigned to unit Tmos.

Figure 4. View from Combs Flat, looking west toward Barnes Butte (center) and the city of Prineville (center-left). Barnes Butte is an Oligocene rhyolite dome complex (~27.5 Ma) and historic Mercury (Hg) prospect. Smith Rock, Grizzly Mountain, and the High Cascades are in the distant skyline.

Publications - 2006  [top]

Ferns, M.L., and McClaughry, J.D. 2006a. Preliminary geologic map of the Huston Lake 7.5 minute quadrangle, Crook County, Oregon. Open file report OFR O-06-21, Oregon Department of Geology and Mineral Industries, Portland, Oregon.  Buy.

Ferns, M.L., and McClaughry, J.D. 2006b. Preliminary geologic map of the Powell Buttes 7.5 minute quadrangle, Crook County, Oregon. Open file report OFR O-06-24, Oregon Department of Geology and Mineral Industries, Portland, Oregon.  Buy.

McClaughry, J.D., and Ferns, M.L. 2006a. Preliminary geologic map of the Prineville 7.5 minute quadrangle, Crook County, Oregon. Open file report OFR O-06-22, Oregon Department of Geology and Mineral Industries, Portland, Oregon.  Buy.

McClaughry, J.D., and Ferns, M.L. 2006b. Preliminary geologic map of the Ochoco Reservoir 7.5 minute quadrangle, Crook County, Oregon. Open file report, OFR O-06-23, Oregon Department of Geology and Mineral Industries, Portland, Oregon.  Buy.

References  [top]

Brown, D.E., Black, G.L., McLean, G.D., and Petros, J.R., 1980, Preliminary geology and geothermal resource potential of the Powell Buttes area, Oregon: Oregon Department of Geology and Mineral Industries Open-File Report O-80-8, 117 p.

Farooqui, S.M., Beaulieu, J.D., Bunker, R.C., Stensland, D.E., and Thomas, R.E., 1981, Dalles Group—Neogene formations overlying the Columbia River Basalt Group in north-central Oregon: Oregon Geology, v. 43, no. 10, p. 131-140.

Ferns, M.L., and McClaughry, J.D., 2006b, Preliminary geologic map of the Powell Buttes 7 ½’ quadrangle, Crook County, Oregon. Open file report OFR O-06-24, Oregon Department of Geology and Mineral Industries, Portland, Oregon.

Gannet, M.W., Lite, K.E., Jr., Morgan, D.S., and Collins, C. A., 2001, Ground-water hydrology of the upper Deschutes basin, Oregon: U.S. Geological Survey water Resources Investigations Report 00-4162, 77 p.

Hodge, E.T., 1942, Geology of north-central Oregon: Corvallis, Oreg., Oregon State College Monongraph, Studies in Geology, No.3.

Hooper, P.R., Steele, W.K., Conrey, R.M., Smith, G.A., Anderson, J.L., Bailey, D.G., Beeson, M.H., Tolan, T.L., and Urbanczyk, K.M., 1993, The Prineville basalt, north-central Oregon: Oregon Geology v. 5, no. 1, p. 3-12.

Lite, K.E. Jr., and Gannett, M.W., 2002, Geologic Framework of the Regional Ground-Water flow System in the Upper Deschutes Basin, Oregon: U.S. Geological Survey Water-Resources Investigations Report 02-4015, 44 p.

Marsh, O.C., 1875, Ancient lake basins of the Rocky Mountain region: American Journal of Science, Ser. 3, v. 9, p. 49-52.

McClaughry, J.D., and Ferns, M.L., 2006a, Preliminary geologic map of the Prineville 7 ½’ quadrangle, Crook County, Oregon. Open file report OFR O-06-22, Oregon Department of Geology and Mineral Industries, Portland, Oregon.

McClaughry, J.D., and Ferns, M.L., 2006b, Preliminary geologic map of the Ochoco Reservoir 7 ½’ quadrangle, Crook County, Oregon. Open file report, OFR O-06-23, Oregon Department of Geology and Mineral Industries, Portland, Oregon.

Merriam, J.C., 1901, A contribution to the geology of the John Day Basin [Oreg.]: University of California Publications, Department of Geology Bulletin, v.2, p. 269-314.

Robinson, J.W., and Price, Don, 1963, Ground water in the Prineville area, Crook County, Oregon: U.S. Geological Survey Water-Supply Paper 1619-P, 49 p.

Robinson, P.T., 1975, Reconnaissance geologic map of the John Day Formation in the southwestern part of the Blue Mountains and adjacent areas, north-central Oregon: U.S. Geological Survey Miscellaneous Investigations Map I-872, scale 1:125,000.

Robinson, P.T., Walker, G.W., and McKee. E.H., 1990, Eocene(?), Oligocene and lower Miocene rocks of the Blue Mountains region, in Walker, G.W., ed., Geology of the Blue Mountains region of Oregon, Idaho, and Washington: U.S. Geological Survey Professional Paper 1437, p. 29-62.

Sherrod, D.R., Taylor, E.M., Ferns, M.L., Scott, W.E., Conrey, R.M., and Smith, G.A., 2004, Geologic Map of the bend 30- 60- Minute Quadrangle, Central Oregon: U.S. Geological Survey Geologic Investigations Series I-2683, 48 p.

Smith, G.A., 1986a, Stratigraphy, sedimentology, and petrology of Neogene rocks in the Deschutes basin, central Oregon: a record of continental-margin volcanism and its influence on fluvial sedimentation in an arc-adjacent basin: Corvallis, Oreg., Oregon State University Ph.D. dissertation, 467 p.

Smith, G.A., 1986b, Simtustus Formation: Paleogeographic and stratigraphic signifigance of a newly defined Miocene unit in the Deschutes basin, central Oregon: Oregon Geology v. 48, no. 6, p. 63-72.

Streck, M.J., 1994, Volcanology and petrology of the Rattlesnake Ash-flow Tuff, eastern Oregon: Corvallis, Oreg., Oregon State University Ph.D. dissertation, 184 p.

Swanson, D.A., 1969, Reconnaissance geologic map of the east half of the Bend quadrangle, Crook, Wheeler, Jefferson, Wasco, and Deschutes Counties, Oregon: U.S. Geological Survey Miscellaneous Investigations Map I-568, scale 1:250,000.

Tolan, T.L., Reidel, S.P., Beeson, M.H., Anderson, J.L., Fecht, K.R., and Swanson, D.A., 1989, Revisions to the estimates of the areal extent and volume of the Columbia River Basalt Group: in Reidel, S.P. and Hooper, P.R., eds., Volcanism and Tectonism in the Columbia River Flood-Basalt Province: Geological Society of America Special Paper 239, p. 1 – 20.

Walker, G.W., 1979, Revisions to the Cenozoic stratigraphy of Harney Basin, southeastern, Oregon: U.S. Geological Survey Bulletin, 1475, 35 p.

Waters, A.C. and Vaughan, R.H., 1968a, Reconnaissance geologic map of the Eagle Rock quadrangle, Crook County, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-540.

Waters, A.C. and Vaughan, R.H., 1968b, Reconnaissance geologic map of the Ochoco Reservoir quadrangle, Crook County, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-541.

Weidenheim, J.P., 1980, The petrography, structure, and stratigraphy of Powell Buttes, Crook County, central Oregon: Corvallis, Oreg., Oregon State University M.S. thesis, 95 p.

Williams, H., 1957, A geologic map of the Bend quadrangle and a reconnaissance geologic map of the central portion of the High Cascade Mountains: Oregon Department of Geology and Mineral Industries map.