The facies and mineralogy of the Tyee Formation of middle Eocene age in the Oregon Coast Range are used to define a paleogeography of part of western Oregon. The formation consists largely of undeformed and unmetamorphosed sandstones, which would be called gray-wackes or wackes by most classifiers. It provides a rare example of a lateral transition from turbidite to nonturbidite sediments; a northern marine turbidite facies can be traced southward into a coeval nearer shore facies. Southern source areas of both the sedimentary material and the turbidity currents can be recognized.

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