Physical Sciences and Mathematics Commons^™

Petrographic Signature For The Whidbey Formation, Jonathan Peterson

WWU Graduate School Collection

The late Pleistocene Whidbey Formation occupies a region on and around Whidbey Island, Washington, that received both northern-derived glacial sediments and eastern-derived nonglacial sediments. Distinguishing between glacial outwash and nonglacial sediments of the Whidbey Formation and the younger Olympia beds has been problematic where stratigraphic sections are incomplete. For the Whidbey Formation, discontinuous deposits of sand, clay, peat and silt that stem from meandering streams on floodplains have not been fully characterized, petrographically. Recent documentation (Dragovich and others, 2005) of dacitic channel and lahar-runout facies on northern Whidbey Island spurred petrographic analysis of various sands from across the whole region …

The Depositional Environment, Petrography, And Tectonic Implications Of Informally Named Middle To Late Eocene Marine Strata, Western Olympic Peninsula, Washington, Benjamin Nickolas Adams

WWU Graduate School Collection

The informally named marine strata examined in this study comprise fault bounded slivers of middle to late Eocene (Ulatizian to Narizian) siltstone, sandstone, and conglomerate exposed on the northwestern Olympic Peninsula. The strata are divided into three lithofacies: the sandstone of Bahobohosh, the siltstone of Waatch Point and the siltstone and sandstone of Bear Creek by Snavley et al. (1986). Six facies have been identified consisting of strata deposited by high- and low-density turbidites, storm waves, slumping, tidal or littoral currents, and debris flows. Relationships among the facies indicate shallow marine deposition that shoaled from below to above storm wave-base …

The Sedimentary Petrography, Depositional Environment And Tectonic Setting Of The Aldwell Formation, Northern Olympic Peninsula, Washington, Keith Marcott

WWU Graduate School Collection

The upper Eocene Aldwell Formation crops out in an east-west trending band across the northern Olympic Peninsula, Washington. Petrographic analyses indicate that the Aldwell Formation has lithologically distinctive eastern and western portions. The rocks of the eastern Aldwell are basalt-rich lithic greywackes; their mean compositions are Qm-F-Lt: 5- 22-73 and polycrystalline quartz-volcanic rock fragments-total sedimentary rock fragments: 1-78-21. The rocks of the western Aldwell are chert-rich lithic arenites; their mean compositions are Qm-F-Lt: 27-19-54 and polycrystalline quartz-volcanic rock fragments-total sedimentary rock fragments: 66-11-23.

Similarities in texture, composition, and alteration products suggest that the basalts of the Crescent seamount province as …