Six early to middle Tertiary geologic units crop out in the
Saddle and Humbug Mountain area. They include the late Eocene to
early Miocene Oswald West muds tones, the lower Silver Point and
the upper Silver Point tongues of the middle Miocene Astoria Formation,
and the middle Miocene Depoe Bay...
Eight Tertiary geologic units crop out in the Seaside-Young's River Falls area, including late Oligocene to early Miocene Oswald West mudstones; Angora Peak sandstone and Silver Point members of the middle Miocene Astoria Formation, and middle Miocene Depoe Bay and Cape Foulweather Basalts. Three new lithologically distinct
units, the 'J'...
Six Tertiary units are exposed in the Onion Peak area near the town of Cannon Beach., Oregon. The units consist of: late Eocene to
early Miocene Oswald West mudstones (informal), middle Miocene Astoria Formation (Angora Peak sandstone and Silver Point mudstone members.-informal), middle Miocene basalts of intrusive and extrusive Depoe...
Six Tertiary rock units are exposed in the Bear Creek-Wickiup Mountain-Big Creek area. They are: the late Oligocene to early Miocene Oswald West mudstones; the Big Creek sandstone member, the Pipeline member (a new unit), and the Silver Point mudstone member of the early to middle Miocene Astoria Formation; and...
Four distinct lithologic units compose the Tertiary rocks of the Neahkahnie Mountain - Angora Peak area, located along the northwest
Oregon coast near the town of Nehalem. The Tertiary units are the late Oligocene to early Miocene Oswald West mudstones, the middle Miocene Angora Peak sandstone member of the Astoria...
Five early to middle Tertiary bedrock geologic units crop out in the study area. These include the late Eocene to early Miocene Oswald West mudstones; the Tucker Creek sandstone, Big Creek sandstone, Silver Point mudstone, and Pipeline members of the
early to middle Miocene Astoria Formation; and the middle Miocene...
Five distinct lithologic units compose the Tertiary rocks in the Tillamook Head - Necanicum Junction area of the northern Oregon Coast Range. They are: the late Eocene to early Miocene Oswald West mudstones, the middle Miocene Angora Peak sandstone and
Silver Point mudstone members of the Astoria Formation, and the...
Twelve rock units, from upper Eocene to middle Miocene are exposed in the Nicolai Mountain-Gnat Creek area. They are, from oldest to youngest: Pittsburg Bluff Formation; Oswald West mudstone; Big Creek sandstone, upper Silver Point mudstone, and
Pipeline mudstone members of the Astoria Formation; Depoe Bay Basalt; Grande Ronde Basalt;...
Eight Tertiary sedimentary and volcanic units crop out in the thesis area. From oldest to youngest they are the: Sager Creek formation (informal); Pittsburg Bluff Formation; Northrup Creek formation (informal); Smuggler Cove formation (informal); Wickiup Mountain and Cannon Beach members (both informal) of the Astoria Formation; the Grande Ronde Basalt,...
The middle to upper Eocene Tillamook Volcanics form the volcanic core or basement rocks in the Rock Creek-Green Mountain area. They consist of a thick sequence of high TiO2 tholeiitic basalt, basaltic andesite, and andesite subaerial flows and breccias. Detailed mapping, petrography, major oxide plots, magnetic polarity, and radiometric age...
The upper Eocene to lower Oligocene Oswald West mudstone is
the oldest formation (informal) in the Green Mountain-Young's
River area. This 1,663 meter thick hemipelagic sequence was deposited
in a low-energy lower to upper slope environment in the Coast
Range forearc basin. The formation ranges from the late Narizian
to...
The middle Eocene Tillamook Volcanics form the oldest rock unit in the Elsie-lower Nehalem River area. K-Ar age determinations and age constraints imposed by foraminiferal and calcareous nannofossil assemblages of overlying sedimentary strata indicate an absolute age of about 42 Ma for the uppermost Tillamook Volcanics. Major oxide values indicate...
The middle to late Eocene tholeiitic Tillamook Volcanics compose the oldest rock unit in the Hamlet-North Fork of the Nehalem River area. Geochemical plots and field relationships indicate that these rocks were produced in an extensional tectonic setting in the developing forearc and formed an extensive tholeiltic oceanic island. The...
Published January 1968. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog