Tukwila Formation

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

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.

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.
 * Triaenodon.sp
 * Mitsukurina.sp

Invertebrate fauna
Are the following:
 * ? Coeloma martinezensis
 * Zanthopsis vulgaris
 * Terebratulina washingtoniana
 * Protula sp.
 * Glycymeris saggittata
 * Venericardia clarki
 * Colwellia bretzi
 * Brisaster sp.