Clastic sedimentary rocks

Locally fossiliferous sandstone and conglomerate; marine fossils indicate Early Cretaceous (Albian) age (Jones, 1960). Includes the Hornbrook Formation of Peck and others (1956), the Grove Creek strata of Jones (1960) and Page and others (1977), Hunters Cove Formation, Cape Sebastian Sandstone, Humbug Mountain Conglomerate, and Rocky Point Formation (Dott, 1971; Blake and others, 1985) and clastic sedimentary rocks on the West Fork of the Illinois River near Waldo (Imlay and others, 1959), about 12 km south of Cave Junction
State Oregon
Name Clastic sedimentary rocks
Geologic age Early to Late Cretaceous
Lithologic constituents
Sedimentary > Clastic > Mudstone (Bed)
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Conglomerate (Bed)
Comments Part of unit in southwesternmost Oregon was mislabeled "Ks" on the State Geologic Map. The Humbug Mountain Conglomerate and Rocky Point Formation are considered part of the Elk Subterrane of the Western Klamath Terrane by Blakc and others (1985); the Houstenaden Creek Formation, Cape Sebastian Sandstone, and Hunters Cove Formation are considered part of the Gold Beach Terrane by Blake and others (1985).
Stratigraphic units Houstenaden Creek Formation

Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000.

Irwin, W.P., 1994, Geologic map of the Klamath Mountains, California and Oregon: U.S. Geological Survey Miscellaneous Investigations Series Map I-2148, scale 1:500,000.

Coleman, R.G., 1972, The Colebrooke Schist of southwestern Oregon and its relation to the tectonic evolution of the region: U.S. Geological Survey Bulletin 1972, 61 p.

Blake, M.C., Jr., Engebretson, D.C., Jayko, A.S., and Jones, D.L., 1985, Tectonostratigraphic terranes in southwest Oregon, in Howell, D.G., ed., Tectonostratigraphic terranes of the circum-Pacific region: Circum-Pacific Council for Energy and Mineral Resources Earth Science Series, v. 1, p. 147-158.

Dott, R.H., Jr., 1971, Geology of the southwestern Oregon coast west of the 124th meridian: Oregon Department of Geology and Mineral Industries Bulletin 69, 63 p.

Koch, J.G., 1966, Late Mesozoic stratigraphy and teconic history, Port Orford-Gold Beach area, southwestern Oregon coast: American Association of Petroleum Geologists Bulletin, v. 50, p. 25-71.

Bourgeois, J., and Dott, R.H., Jr., 1985, Stratigraphy and sedimentology of Upper Cretaceous rocks in coastal southwest Oregon: Evidence for wrench-fault tectonics in a postulated accretionary terrane: Geological Society of America Bulletin, v. 96, p. 1007-1019.

Nilsen, T.H., 1993, Stratigraphy of the Cretaceous Hornbrook Formation, southern Oregon and northern California: U.S. Geological Survey Professional Paper 1521, 89 p.

Imlay, R.W., Dole, H.M., Wells, F.G., and Peck, D., 1959, Relations of certain Upper Jurassic and Lower Cretaceous formations in southwestern Oregon: American Association of Petroleum Geologists Bulletin, v. 43, p. 2770-2785.

Jones, D.L., 1960, Lower Cretaceous (Albian) fossils from southwestern Oregon and their paleogeographic significance: Journal of Paleontology, v. 34, no. 1, p. 152-160.

Peck, D.L., Imlay, R.W., and Popenoe, W.P., 1956, Upper Cretaceous rocks of parts of southwestern Oregon and northern California: American Association of Petroleum Geologists Bulletin, v. 40, no. 8, p. 1968-1984.

Page, N.J., Blair, W.N., Gray, Floyd, Cannon, J.K., Grimes, D.J., and Leinz, R.W., 1977, Preliminary reconnaissance geologic map of the Wimer quadrangle, Oregon: U.S. Geological Survey Miscellaneous Field Studies Map MF-848, scale 1:62,500.

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Counties Jackson - Josephine