Tertiary dunite intrusive rocks (WATd;0)

State	Washington
Name	Tertiary dunite intrusive rocks
Geologic age	Late Cretaceous
Original map label	Td
Comments	May be referred to no more specifically that as peridotite; may also be reported as harzburgite. Occurs as pods, lenses, and "tectonically emplaced bodies" (Dragovich and others, 2002); Twin Sisters Dunite is a "plate-like body" (Tabor and others, 1994). Pyroxenite occurs very rarely.
Primary rock type	dunite
Secondary rock type	serpentinite
Other rock types	serpentinite
Lithologic constituents	Major Igneous > Plutonic > Ultramafic > Peridotite > Dunite Minor Metamorphic > Serpentinite Incidental Igneous > Plutonic > Ultramafic > Pyroxenite
Map references	Huntting, M. T., Bennett, W. A. G., Livingston, V. E. Jr., Moen, W. S., 1961, Geologic Map of Washington: Washington Division of Mines and Geology, scale 1:500,000.
Unit references	Huntting, M. T., Bennett, W. A. G., Livingston, V. E. Jr., Moen, W. S., 1961, Geologic Map of Washington: Washington Division of Mines and Geology, scale 1:500,000. Dragovich, J. D., Logan, R. L., Schasse, H. W., Walsh, T. J., Lingley, W. S., Jr., Norman, D. K., Gerstel, W. J., Lapen, T. J., Schuster, J. E., Meyers, K. D., 2002, Geologic Map of Washington-Northwest Quadrant: Washington Division of Geology and Earth Resources Geologic Map GM-50, scale 1:250,000. Tabor, R. W., Haugerud, R. A., Booth, D. B., Brown, E. H., 1994, Preliminary Geologic Map of the Mount Baker 30- by 60-Minute Quadrangle, Washington: U. S. Geological Survey Open File Report 94-403, 55p., 2 pls. [http://pubs.er.usgs.gov/publication/ofr94403] Tabor, R. W., Booth, D. B., Vance, J. A., Ford, A. B., Ort, M. H., 1988, Preliminary geologic map of the Sauk River 30 by 60 minute quadrangle, Washington: U. S. Geological Survey Open File Report 88-692, 51 p., 1 pl. [http://pubs.er.usgs.gov/publication/ofr88692]
Geographic coverage	Skagit - Snohomish - Whatcom