Saddle Mountain, Mattawa, Grant Co., Washington, USA
|Latitude & Longitude (WGS84):||46° 48' 28'' North , 119° 53' 25'' West|
|Latitude & Longitude (decimal):||46.807671, -119.890225|
petrified wood and bog locality
Rock Types RecordedEntries shown in red are rocks recorded for this region.
|- Miocene - 23.03 Ma||Frenchman Springs Member, Wanapum Basalt|
Basalt flows (Frenchman Springs Member [CRB, WB])
|Pliocene - Miocene2.588 - 23.03 Ma||Miocene-Pliocene volcanic rocks|
May include hypabyssal intrusions.
|Early Pliocene - Late Oligocene3.6 - 28.1 Ma||Miocene volcanic rocks|
Dark-gray to black, dense aphanitic basalt flows; commonly columnar jointed, less commonly irregularly and platy jointed; some flows vesicular, grading to scoriaceous; includes minor pillow lava, palagonite beds, and interbedded soil profiles and sedimentary beds; contains diatomite beds locally. Maximum thickness in south-central Washington may be in excess of 10,000 feet; much thinner in western Washington, where flows are mostly associated with marine sedimentary rocks. Includes acidic and intermediate volcanic rocks in northern Cascade Mountains.
Yakima basalt used by some workers interchangably with Columbia River Basalts, by others as specific formation or subgroup within the Columbia River Basalt Group. Entire unit consists of basalt flows with minor exceptions: outcrop of andesite and basalt flows in southwestern Washington near Silver Lake and outcrops of basalt, dacite, andesite, and rhyolite breccia and tuff (including Hannegan volcanics and Skagit volcanics) with volcanic and tuffaceous conglomerate and sandstone in northwestern Washington near Mt. Baker. Any sedimentary interbeds included in this unit, especially in eastern Washington, probably of, or correlative to, the Ellensburg Formation (see WAMPLc and WAOLc) or the Latah Formation (see WAMc); in western Washington, may be of, or correlative to, the Astoria Formation (see WAMPL and WAM).
|Miocene5.333 - 23.03 Ma||Miocene volcanic: mafic rocks|
Volcanic: mafic rocks
References for regional geology:
Data provided by Macrostrat.org
Garrity, C.P., and Soller, D.R.,. Database of the Geologic Map of North America: adapted from the map by J.C. Reed, Jr. and others (2005). U.S. Geological Survey Data Series 424 .
USGS compilers. State geologic map data. State Maps.
Geological Survey of Canada. Generalized geological map of the world and linked databases. doi:10.4095/195142. Open File 2915d.
Washington State Department of Natural Resources, Division of Geology and Earth Resources. Washington Interactive Geologic Map: 1:100,000 scale. Washington Division of Geology and Earth Resources.
2 valid minerals.