U.S. Geological Survey Home AASG Logo USGS HOME CONTACT USGS SEARCH USGS
National Geologic Map Database
Geologic Unit: Yonna
Search archives
Map showing publication footprint
  • Usage in publication:
    • Yonna formation*
  • Modifications:
    • Named
    • Biostratigraphic dating
  • Dominant lithology:
    • Diatomite
    • Sandstone
    • Siltstone
    • Ash
    • Tuff
  • AAPG geologic province:
    • Great Basin province
Publication:

Newcomb, R.C., 1958, Yonna formation of the Klamath River basin, Oregon: Northwest Science, v. 32, no. 2, p. 41-48.


Summary:

Type locality designated along west side of Yonna Valley, T38S R11.5E, Klamath Co, OR. Crops out in large areas in Yonna, Swan Lake, Sprague River, Williamson River, Poe, and Klamath Valleys and adjacent Lost River Basin. In type area consists of (1) lower sedimentary (lacustrine) section of ashy diatomite, stratified sandstone, laminated siltstone, waterlaid volcanic ash, pumice, and semiconsolidated gravel, and (2) rather thick upper unit of basaltic lapilli tuff, part of which was deposited in water. Is as much as 2000 ft thick. Cut by dikes and sills of generally basaltic composition and is broken by intricate system of block faulting. Overlies unnamed lava rocks; underlies with minor erosional unconformity lava rocks (Pliocene?), Quaternary lava or alluvium. Age is Pliocene on basis of fresh-water mollusks identified by Ten-Chien Yen (USGS), diatoms identified by K.E. Lohman (Geological Survey), and peccary skull, PROSTHENOPS OREGONSIS Colbert (middle Pliocene) identified by Jean Hough (USGS).

Source: GNU records (USGS DDS-6; Menlo GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Yonna Formation*
  • Modifications:
    • Age modified
    • Geochronologic dating
  • AAPG geologic province:
    • Great Basin province
Publication:

Pickthorn, L.B.G., and Sherrod, D.R., 1990, Potassium-argon ages from Klamath Falls area, south-central Oregon: Isochron/West, no. 55, p. 13-17.


Summary:

Unit age modified to: latest Miocene to early Pliocene based on K-Ar ages of underlying and overlying basalt lava flows between 5.5 and 3.6 Ma. "This indicates a latest Miocene to early Pliocene age for mammalian and fish fossil localities of Newcomb (1958)."

Source: GNU records (USGS DDS-6; Menlo GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Yonna Formation†
  • Modifications:
    • Abandoned
  • AAPG geologic province:
    • Great Basin province
Publication:

Search archives

For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).

Slash (/) indicates name does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).