Pre-Tertiary dunite intrusive rocks

Dunite associated with serpentine on Cypress Island in San Juan Islands and on Mount Chopaka near Oroville in Okanogan County.
State Washington
Name Pre-Tertiary dunite intrusive rocks
Geologic age Middle Jurassic
Lithologic constituents
Igneous > Plutonic > Ultramafic > Peridotite > Dunite
Comments Huntting and others, 1961, does not map any WApTd unit on Mount Chopaka (there is WApTb, however, which contains peridotite).
Stratigraphic units Fidalgo Complex (in part)

Huntting, M.T., Bennett, W.A.G., Livingston, V.E.Jr., and 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.

NGMDB product
Counties Skagit