Tukwila Formation

The Tukwila Formation is a geological formation in King County, Washington within the Puget Group. It is named after the Tukwila area, which is close to the formation. The formation consists of various fossils of marine origin.^[1]

Tukwila Formation
Stratigraphic range: Bartonian
Type	Geological formation
Location
Region	Washington
Country	United States
Type section
Named for	Tukwila, Washington

King County Geologic Cross Section

King County Geologic Map

The Tukwila Formation is mainly composed of andesitic to dacitic volcanic sandstone, siltstone, shale, tuff breccia, tuff, lahar, and carbonaceous shales. The tuff breccia has an approximate age of 42 Ma.^[2]

Fauna

Vertebrate fauna

Vertebrate fauna mainly consists of just shark remains. Mainly one unnamed species of Goblin shark and one unnamed species belonging to the same genus as the Whitetip reef shark.^[3][4]

• Triaenodon.sp
• Mitsukurina.sp

Invertebrate fauna

Are the following:^{[citation needed]}

• ? Coeloma martinezensis
• Zanthopsis vulgaris
• Terebratulina washingtoniana
• Protula sp.
• Glycymeris saggittata
• Venericardia clarki
• Colwellia bretzi
• Brisaster sp.