Identification_Information: Citation: Citation_Information: Originator: Russell Evarts, U.S. Geological Survey, Research Geologist Publication_Date: 2016 Title: Sauvie_Island Description of Map Units Geospatial_Data_Presentation_Form: tabular digital data Other_Citation_Details: Pre-Digital Review stage metadata Description: Abstract: DESCRIPTION OF MAP UNITS SURFICIAL DEPOSITS af Artificial fill (Holocene) Unconsolidated soil, sand, gravel underlying industrialized floodplain areas of north Portland and Vancouver; mounds of sand and minor gravel from channel dredging flanking the Columbia River; and earth and crushed rock for highway and railroad beds, levees, and small dams Qtf Fan deposits from tributaries (Holocene) Unconsolidated silt, sand, and gravel in small fan-shaped accumulations from steep drainages from in Tualatin Mountains. Most fans younger than 2000 years, inferred from relation with Columbia and Willamette River floodplain deposits. Poorly exposed but likely composed of silt, sand, and gravel diamicts deposited by debris flow and stratified sediment deposited by streamflow Qa Floodplain deposits of tributaries (Holocene and Pleistocene) Unconsolidated sand, gravel, and organic-rich mud along rivers and creeks within the Tualatin Mountains. Locally upstream of landslides, indicating deposition in landslide-dammed valley bottoms Qe Eolian deposits (Holocene) Unconsolidated, massive fine sand and silt forming dunes and benches cresting up to 24 m (79 ft) above sea level. Mostly quartzofeldspathic sand containing muscovite and minor lithic fragments. Forms undulating, apparently wind-fluted topography of southwestern Sauvie Island and locally mantles low benches at base of Tualatin Mountains (where mapped bodies may include compositionally similar cataclysmic-flood deposits, sand and silt facies (Qfs). No evidence of modern sand accumulation or dune activity. Oxidized surface soils as thick as 2 m on Sauvie Island dunes indicate stability for hundreds or thousands of years. Well logs indicate dune sand generally extends down to 1020 m below sea level, locally to 30 m below sea level. This suggests they began forming as long as 9000 years ago according to elevations of dated Holocene floodplain deposits along the lower Willamette River (Peterson and others, 2011). Likely formed by easterly winds entraining Columbia and Willamette River beach and bar sands during periods of low water Columbia River and Willamette River floodplain deposits (Holocene and Pleistocene) Unconsolidated sediment of floodplain, islands and bars of the Columbia and Willamette Rivers at elevations mostly less than 10 m (30 ft) above sea level; composed largely of quartz, feldspar, and conspicuous muscovite, indicating Columbia River provenance. Upper elevation of deposits approaches limits of historical flooding before 20th-century river regulation and floodplain diking. Most deposits above modern low-water river level (about 1.5 m (5 ft) above sea level in map area) are younger than 2000 years. Deposits at depth likely to be as old as 16 ka (Baker and others, 2010). Well logs and seismic reflection profiles show that fine-grained valley fill beneath the historic flood plain locally extends to 6570 m (210230 ft) below sea level in and near the map area(Gates, 1994; Pratt and others, 2001; Peterson and others, 2011). These deposits resulted from river aggradation since the last-glacial sea level low stand of about 16 ka Qcwf Silt and clay facies Silt, clay, and minor sand deposited on low-lying areas of the Columbia River flood plain at elevations below 3 m (10 ft). Includes areas of drained lake beds on Sauvie Island. Bank exposures, auger holes, and trenches show silt, clay, and organic materials in horizontal laminae typically 120mm thick Qcwc Sand facies Sand and silt of ridge and swale topography and natural levees flanking floodplain channels, commonly up to 9 m (30 ft) above sea level. Ridges and swales consist of en-echelon point bars or natural levees showing migration of Columbia River and secondary channels like Multnomah Channel. Exposed stratigraphy outside map area shows stratified fine to medium sand, in layers as thick as 30 cm alternating with silty sand. Subhorizontal and inclined beds indicate deposition by both vertical and lateral accretion. Higher sandy deposits flanking meandering floodplain channels are natural levees and crevasse splays from overbank flooding Qls Landslide deposits (Holocene and Pleistocene) Diamicts of angular bedrock and surficial debris transported down slope en masse by semi-coherent slumps, rockslides, earthflows, and debris-flows. Many mapped slides head at arcuate scars and exhibit subhorizontal tops, bulbous toes, and hummocky, surfaces. Large landslide complexes along McCarthy Creek Qtd Terrace deposits (Holocene and Pleistocene) Unconsolidated silt, sand, and gravel forming benches along McCarthy Creek in the Tualatin Mountains. Not exposed in map area but mapped by morphology. Likely stratified deposits of streams diamicts of debris flows Qlo Loess (Holocene? and Pleistocene) Massive unconsolidated deposits of light-gray to buff, micaceous, quartz-feldspathic eolian clay, silt and fine sand on uplands of Tualatin Mountains; contains granules and small pebbles; locally capped with strongly developed red soils. Forms mantle up to 12 m thick along ridge top southwest of Multnomah Channel, overlying Sentinel Bluffs Member of the Grand Ronde Basalt. Probably deposited during several episodes throughout late Quaternary time; luminescence ages from similar loess deposits outside map area range from greater than 79 ka to 39 ka. Radiocarbon ages on eolian silt on uplands near Ridgefield, east of the map area, indicate episodic deposition through the Holocene (Punke and others, 2011). Equivalent to loess of Trimble (1963) and the Portland Hills Silt of Lentz (1981) Qfs Cataclysmic-flood deposits, sand and silt facies (Pleistocene) Unconsolidated light brown to light gray silt, clay, and fine to medium sand. Mappable accumulations sparse in map area but thin deposits likely discontinuously mantle surfaces up to 120 m (400 ft) elevation in the Tualatin Mountains. Difficult to map because of similar appearance and composition to loess covering most upland surfaces. Fresh exposures regionally show many, 0.25-to-1.5-m thick, fining up sequences of ripple cross-stratified very fine sand grading up to massive bioturbated clayey silt, locally as thick as 30 m. Sand composed of quartz, feldspar, basalt fragments, and mica shows Columbia River provenance. Interpreted as slack-water sediment settled from temporarily ponded floodwaters during colossal outburst floods caused by repeated failure of ice dam at Clark Fork River that formed Pleistocene Lake Missoula in western Montana (Bretz, 1925, 1959; Bretz and others, 1956; Trimble, 1963; Allison, 1978; O'Connor and Baker, 1992; Benito and O'Connor, 2003). Regionally correlates with Trimbles (1963) Quaternary lacustrine deposits. Radiocarbon and tephrochronologic data outside map area indicate depositional ages of 20 to 15 ka (Waitt, 1985, 1994; Atwater, 1986; Benito and O'Connor, 2003; Clague and others, 2003; O'Connor and Benito, 2009). Regionally, coarse bedload deposits and fine slack- water deposits mapped separately (Evarts and OConnor, 2008, 2013), but only fine facies present in map area BASIN-FILL DEPOSITS QTc Unnamed conglomerate (Pleistocene and Pliocene?)Unconsolidated to semi-consolidated, pebble conglomerate. Underlies Oak Island and benches up to 15 m (50 ft) elevation in northwest part of map area. Oak Island exposure apparently correlates with subsurface gravel surface separating deeper fine-grained fill beneath Multnomah Channel and Columbia River, and probably contiguous in the subsurface with the benches in the northwest part of the map area that extend north as a broad gravel terrace underlying Scappoose (Evarts, 2004a; Gates, 1994; fig. 4, cross section A-A'). Sparse well-log data show the gravel locally thicker than 41 m. Poorly exposed in map area, but better exposures in gravel quarries near Scappoose to the north show subhorizontal layers 0.52 m thick of clast-supported round-cobble gravel with sandy matrix. Cobbles are diverse lithologies, including quartzite and granitic rocks of upper Columbia River provenance. Layers locally defined by sets of north- dipping foresets, and are in places separated by horizontal lenses of micaceous quartzofeldspathic sand as thick as 30 cm. Many fine- grained volcanic clasts in the surficial oxidized zone have weathering rinds of 26 mm, and rare clasts have rinds as thick as 1 cm. No age data from within the map area, but clast weathering, overlying cataclysmic-flood deposits, and luminescence ages from quarries near Scappoose indicate a late Quaternary age of 80 to 15 ka for the upper 8 m of this gravel, deeper gravel may be much older Tsr Sandy River Mudstone (Miocene and Pliocene) Shown on cross sections only. Semiconsolidated well-bedded sandstone, siltstone, claystone, and minor quartzite-bearing conglomerate, pumice-lapilli tuff, and lignite. Planar and trough crossbeds and cut-and-fill structures within sandy horizons indicate fluvial deposition. Age poorly known but probably middle Miocene to late Pliocene from relations elsewhere in Portland Basin (Evarts, 2004c; Evarts and O'Connor, 2008; Evarts and others, 2009a) Ttfc Troutdale Formation, conglomerate member (Pliocene and (or) Miocene) Consolidated, well sorted, clast-supported, pebble and cobble conglomerate. Composed largely of well-rounded clasts of Columbia River Basalt Group and minor but persistent quartzite and granitic and felsic metamorphic rocks. Sparse interbeds of volcanic lithic and micaceous quartzofeldspathic sandstone. Poorly exposed in map area; mapped on flanks of Tualatin Mountains where well logs indicate cemented gravel and sand overlie the Columbia River Basalt Group and temporary construction exposures show sand and gravel intensely weathered to depths of several meters. Equivalent in part to upper member of Mundorff (1964) and to lower member of Tolan and Beeson (1984) of the Troutdale Formation. Late Miocene to early Pliocene age inferred from stratigraphic relations outside quadrangle (Trimble, 1963; Tolan and Beeson, 1984) BEDROCK COLUMBIA RIVER BASALT GROUP Grande Ronde Basalt (Miocene) Light-gray to black flows of tholeiitic basaltic andesite; vesicular to microvesicular, aphyric to microphyric to very sparsely plagioclase-phyric; exhibit relatively low-TiO2 characteristic of the Grande Ronde Basalt of the Columbia River Basalt Group (Swanson and others, 1979; Mangan and others, 1986; Beeson and others, 1989; Reidel and others, 1989; Reidel and Tolan, 2013). Flows in this quadrangle deeply weathered; where exposed in roadcuts and quarries, display hackly (entablature) to blocky to columnar jointing patterns and vesicular flow tops; pillow lava locally present at base. Typical samples intergranular to intersertal, containing lathlike plagioclase, granular clinopyroxene, and Fe-Ti oxide crystals in sparse to abundant dark glass; some flows contain rare plagioclase phenocrysts and glomerocrysts to 5 mm long. Textures resemble those described by Long and Wood (1986) for correlative flows in the Columbia Basin. Basalt issued from vents in eastern Columbia Basin and entered northwestern Oregon and southwestern Washington through a wide gap in the Cascade Range (Tolan and others, 1989; Wells and others, 1989; Beeson and Tolan, 1990). 40Ar/39Ar age determinations (Barry and others, 2010, 2013, Baksi, 2013) indicate emplacement of Grande Ronde flows at about 16 Ma. Nomenclature is from Reidel and Tolan (2013) and Reidel (2005) Tgsb Sentinel Bluffs Member Aphyric to sparsely phyric basaltic andesite flows forming uppermost member of the Grande Ronde Basalt, within the N2 magnetostratigraphic unit of Swanson and others (1979). Distinguished from all other Grande Ronde Basalt flows in the N2 magnetostratigraphic unit by relatively high MgO and Cr contents and normal magnetic polarity (Reidel and others, 1989; Reidel, 2005). Owing to deep weathering and extensive loess cover, unit not exposed in map area, and distribution inferred from relations in adjacent quadrangles (Evarts, 2004a; Madin and Niewendorp, 2008; Madin and others, 2008) Tgww Winter Water Member Sparsely plagioclase-phyric to glomerophyric basaltic andesite flows with relatively low MgO contents (3.4 to 3.9 wt percent) and moderate TiO2 contents (2.0 to 2.2 wt percent). Contains scattered plagioclase phenocrysts and glomerocrysts 1 to 3 mm across in aphyric to sparsely microphyric groundmass. Exhibit normal magnetic polarities with low inclinations (commun., 2010); Stratigraphic position and petrographic, chemical and paleomagnetic characteristics indicate equivalence to Winter Water Member (Reidel and Tolan, 2013), within the N2 magnetostratigraphic unit of Swanson and others (1979). At least 30 m thick where exposed in Angell quarry near south edge of map area. Most analyzed samples from map area highly weathered (denoted by low totals and (or) anomalously low iron contents fresher samples indicate two chemically distinguishable flows are present in map area: one has MgO about 3.9wt percent, TiO2 about 2.05 wt percent, and Ba percent, TiO2> 2.10, and Ba>600 ppm. Distribution in map area, especially north of McCarthy Creek, uncertain owing to poor exposure Tgo Ortley member of Reidel and Tolan (2013) Flows of aphyric, intersertal to intergranular basaltic andesite with relatively low MgO (3.5 to 3.6 wt percent) and TiO2 (1.95 wt percent) contents and normal magnetic polarity (J.T. Hagstrum, written commun., 2010). Stratigraphic position and petrographic, chemical, and paleomagnetic characteristics indicate equivalence to informal Ortley member of Reidel and Tolan (2013), within the N2 magnetostratigraphic unit of Swanson and others (1979). Four flow units totaling about 65 m thick exposed in Angell quarry; base of uppermost flow is pillow lava. Most analyzed samples from map area, even those from quarry, are highly weathered (denoted by low totals and (or) iron contents < 11 wt percent FeO*) Tggc Grouse Creek member of Reidel and Tolan (2013) Flows of aphyric basaltic andesite exposed only in Angell quarry where three flows total 35 m thick. Uppermost flow is about 40 m thick and reversely magnetized; overlies columnar-jointed flow about 6 m thick, which in turn overlies about 3 m of hackly-jointed lowest flow. Chemical analyses show that only the lower two flows are relatively fresh; their compositions resemble those of Grouse Creek flows mapped elsewhere in western Oregon (R.E. Wells, unpub. data, R.C. Evarts, unpub.data) Tsf Scappoose Formation(Oligocene) Shown on cross sections only. Shallow marine, tuffaceous, micaceous, arkosic sandstone; underlies Grande Ronde Basalt to west and northwest of map area (Madin and Niewendorp, 2008; M.G. Sawlan, oral commun, 2013). Abundant molluscan fauna indicate late Oligocene age (Warren and Norbisrath, 1946) Purpose: The description of map units table for the polygons that represent the units on the geology map. Keywords: Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: Table of description of map units. Access_Constraints: None Use_Constraints: Users of this geospatial database and geologic information derived from it should acknowledge the U.S. Geological Survey as the source of the data. Uses of this digital geologic map should not violate the spatial resolution of the data. Although the digital form of the data removes the constraint imposed by the scale of a paper map, the detail and accuracy inherent in map scale are also present in the digital data. The fact that this database was edited for a scale of 1:24,000 means that higher resolution information is not present in the dataset. Plotting at scales larger than 1:24,000 will not yield greater real detail, although it may reveal fine-scale irregularities below the intended resolution of the database. Similarly, 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: U.S. Geological Survey Contact_Person: Russell C. Evarts Contact_Position: Geologist Contact_Address: Address_Type: mailing and physical Address: 345 Middlefield Rd. MS-973 City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: US Contact_Voice_Telephone: 650-329-4929 Contact_Electronic_Mail_Address: revarts@usgs.gov Contact_Instructions: GIS Data_Set_Credit: Evarts, Russell C., O'Connor, Jim E., and Cannon, Charles M. (authors). Database by Joseph F. Mangano, Karen L. Wheeler, and Charles M. Cannon Native_Data_Set_Environment: Microsoft Windows XP Professional x64 Edition Version 5.2 (Build 3790) Service Pack 2; Esri ArcGIS 10.1.0.3035 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: Sauvie_DMU Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: Esri Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: Unit_Name Attribute: Name of geologic unit used in map. Attribute_Label: Unit_Symbol Attribute: Short abbreviation used for the map to represent the longer geologic unit name. Attribute_Label: Unit_Description Attribute: A lengthy description of the geologic unit also found in the pamphlet. Attribute_Label: Unit_Geologic_Age Attribute: Age of the geologic unit. Attribute_Label: Type_of_deposit Attribute: Type of deposit Attribute_Label: Unit_order_dmu Attribute: Order of the unit in the Description of Map Units found in the pamphlet. Attribute_Label: Unit_information Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: USGS Information Services Contact_Address: Address_Type: mailing address Address: Box 25286, Denver Federal Center City: Denver State_or_Province: CO Postal_Code: 80225-0046 Country: USA Contact_Voice_Telephone: (303) 202-4200 Contact_Voice_Telephone: 1-888-ASK-USGS Contact_Facsimile_Telephone: (303) 202-4695 Contact_Electronic_Mail_Address: infoservices@usgs.gov Resource_Description: Downloadable Data USGS Scientific Investigations Map SIM 3349 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 rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, 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_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://dx.doi.org/10.3133/sim3349 Fees: free Metadata_Reference_Information: Metadata_Date: 20160119 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Pacific Northwest Urban Corridor Mapping Project Contact_Person: Russell C. Evarts Contact_Address: Address_Type: mailing and physical address Address: 345 Middlefield Rd Address: MS 973 City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: USA Contact_Voice_Telephone: (650) 329-4929 Contact_Facsimile_Telephone: (650) 329-4936 Contact_Electronic_Mail_Address: revarts@usgs.gov Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: local time