| Tukwila Formation | |
|---|---|
| Stratigraphic range: Bartonian | |
| Type | Geological formation |
| Location | |
| Region |  Washington |
| Country |  USA |
| Type section | |
| Named for | Tukwila, Washington |
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.[1]
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]
- ^ "STRATIGRAPHY OF EOCENE ROCKS IN A PART OF KING COUNTY, WASHINGTON" (PDF). U. S. Geological Survey, Menlo Park, California.
- ^ Booth, Derek; Walsh, Timothy; Troost, Kathy; Shimel, Scott. "Geologic Map of the East Half of the Bellevue South 7.5' x 15' Quadrangle, Issaquah Area, King County, Washington,U.S. Geological Survey Scientific Investigations Map 3211, scale 1:24,000" (PDF). USGS. Retrieved 27 May 2020.