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Geologic Unit: Kachess
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Map showing publication footprint
  • Usage in publication:
    • Kachess rhyolite*
  • Modifications:
    • Named
  • Dominant lithology:
    • Rhyolite
  • AAPG geologic province:
    • Cascades province
Publication:

Smith, G.O., and Calkins, F.C., 1906, Description of the Snoqualmie quadrangle, Washington: U.S. Geological Survey Geologic Atlas of the United States Folio, Snoqualmie folio, no. 139, 14 p., scale 1:125,000


Summary:

Unit is named the Kachess rhyolite, for Kachess Lake, [Kachess Lake 7.5' quad] Kittitas Co., WA. Consists of several thick flows of white or yellow acidic lava. Throughout a large part of its extent it is separated by interbedded sandstones and basalts into several distinct rhyolitic sheets. Elsewhere these sheets merge together, and cannot be distinguished as separate units. Maximum thickness is 4,000 ft. Conformably overlies and in places is interbedded with the Naches formation (new); Conformably underlies the Teanaway basalt. Age is Eocene.

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


Map showing publication footprint
  • Usage in publication:
    • Kachess Rhyolite†
  • Modifications:
    • Abandoned
  • AAPG geologic province:
    • Cascades province
Publication:

Tabor, R.W., Frizzell, V.A., Jr., Vance, J.A., and Naeser, C.W., 1984, Ages and stratigraphy of lower and middle Tertiary sedimentary and volcanic rocks of the central Cascades, Washington; application to the tectonic history of the Straight Creek Fault: Geological Society of America Bulletin, v. 95, no. 1, p. 26-44.


Summary:

Kachess Rhyolite is abandoned. Rocks previously assigned to the Kachess are reassigned to the Silver Pass Volcanic Member (new) of the Swauk Formation.

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


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

Asterisk (*) indicates published by U.S. Geological Survey authors.

"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 conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).

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