The Moxee City (Washington) mammoth: Morphostratigraphic, taphonomic, and taxonomic considerations

Authors

Karl Lillquist, Central Washington University
Steve Lundblad
Bax R. Barton, University of Washington, Seattle

Document Type

Article

Department or Administrative Unit

Geography

Publication Date

10-2005

Abstract

A nearly complete, but highly fractured, proboscidean tusk was unearthed during parking lot construction near Moxee City in central Washington in May 2001. Schreger angle analysis revealed that the tusk was from a mammoth. AMS radiocarbon dating of the tusk established that the mammoth died 14,570 ¹⁴C yr BP. The age, combined with the biogeography of proboscidean finds in the Pacific Northwest, suggests the tusk is from a Columbian mammoth (Mammuthus columbi). The condition of the tusk and its association with basalt and crystalline erratics suggest that a locally derived tusk was swept up in the advancing flood and transported to ~320 m elevation, where it was deposited in the sediments of the 3rd of 3 Missoula Floods that are preserved in the area. The tusk's weathering indicates subaerial exposure prior to burial in the slackwater sediments. Slackwater deposits at the site are pale, ~30–100 cm thick, calcareous, fine-textured strata that include occasional coarse basalt and crystalline sand and gravel. They are intruded by numerous clastic dikes. The sediments encapsulating the tusk lack rhythmites because of their deposition in the nearshore zone of an ephemeral slackwater lake. The first 2 floods inundated the site between 15,300 ¹⁴C yr BP and 14,570 ¹⁴C yr BP, stripping the A horizon from a well-developed soil formed in alluvial fan sediments sitting above an Ellensburg Formation pediment. The last flood to reach the site occurred later than 14,570 ¹⁴C yr BP, as indicated by the presence of the dated tusk. Post-flood and post-MSH S tephra loess derived from the Yakima River floodplain mantles these slackwater deposits. The Warden soil is forming in the now-stable loess parent material.

Comments

This article was originally published in Western North American Naturalist. The full-text article from the publisher can be found here.

Recommended Citation

Lillquist, Karl; Lundblad, Steve; and Barton, Bax R., "The Moxee City (Washington) mammoth: Morphostratigraphic, taphonomic, and taxonomic considerations" (2005). All Faculty Scholarship for the College of the Sciences. 327.
https://digitalcommons.cwu.edu/cotsfac/327

Journal

Western North American Naturalist

Rights

Brigham Young University © 2005