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Stratigraphy And Petrology Of The Nooksack Group In The Glacier Creek-Skyline Divide Area, North Cascades, Washington, Jon Niels Sondergaard
Stratigraphy And Petrology Of The Nooksack Group In The Glacier Creek-Skyline Divide Area, North Cascades, Washington, Jon Niels Sondergaard
WWU Graduate School Collection
The 6-7 kilometer thick Upper Jurassic-Lower Cretaceous Nooksack Group is divided informally into four units on the basis of lithology. The basal unit consists of tuffaceous sandstone and keratophyric tuff with minor intercalations of argillite and intermediate crystalline volcanic rocks. The lower unit is composed of interbedded black argillite and volcaniclastic sandstone. The middle unit consists of thick-bedded volcaniclastic sandstone and coarse, sedimentary breccia with minor argillite. The upper unit is comprised of interbedded black argillite and volcaniclastic sandstone.
Lithologies and sedimentary structures within these units suggest: (1) the lower and upper units represent depositional lobe deposits of a middle …