- Usage in publication:
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- Echo Park Alluvium*
- Modifications:
-
- Named
- Dominant lithology:
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- Alluvium
- AAPG geologic province:
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- Denver basin
Summary:
Named for exposures in Echo Park on north side of Arkansas River in central part of T18S, R73W, Fremont Co., CO in the Denver basin. Type locality designated along Echo Canyon, 1 3/4 mi to 3 1/2 mi north from Arkansas river. Consists of poorly sorted, reddish-brown weathered, crudely stratified, partially consolidated clay to boulder-size clasts (20 ft in diameter) that are chiefly Precambrian plutonic igneous and metamorphic rocks of local derivation set in a matrix of micaceous sand, silt, and clay. Is 900 ft thick at type; 1,100 ft penetrated in subsurface. Deposited in a graben on fault blocks of Precambrian rocks. Underlies Wall Mountain Tuff at type. Represents an alluvial sheet-wash deposit in paleovalleys or downfaulted basins. Eocene age based on stratigraphic position beneath Wall Mountain (35-36 m.y.). May correlate with Huerfano Formation and Farisita Conglomerate.
Source: GNU records (USGS DDS-6; Denver 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 ([ ]).