- Usage in publication:
-
- Root Glacier Formation*
- Modifications:
-
- Named
- Biostratigraphic dating
- Dominant lithology:
-
- Mudstone
- Siltstone
- Conglomerate
- Graywacke
- AAPG geologic province:
-
- Alaska Southern region
Summary:
Named for exposures on arete-like ridges bordering Root Glacier. Type locality designated as hillside east of upper part of McCarthy Creek, McCarthy C-5 quad, southern AK. Extends northwestward across McCarthy C-6 and toward northeast corner of McCarthy C-7 quads. Consists mainly of clastic rocks, mudstone and siltstone, less abundant graywacke, arenite, shale, and well-indurated pebble and cobble conglomerate unit. Estimated thickness is from 1300 to 4000 ft. Disconformably overlies Nizina Mountain Formation or locally Lubbe Creek Formation. Unconformably underlies Wrangell Lava or Quaternary surficial deposits. Age is Late Jurassic (late Oxfordian and Kimmeridgian) based on paleontologic studies by R.W. Imlay; list of fossils included in report.
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 ([ ]).