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.
related
Renton Formation (Wikipedia)The Renton Formation is a geologic formation in Washington (state) within the Puget Group. It preserves fossils dating back to the Paleogene period.