Named for rocks exposed on both sides of Eagle Gulch, Saguache Co, CO in San Luis basin. No type locality designated. Composed of a gray massive rock properly called quartz latite with a fine-grained groundmass. Has phenocrysts of orthoclase and smaller plagioclase phenocrysts. Lacks flow and rhyoclastic structure. No fragments of andesite enclosed. Is of Tertiary age.
Source: GNU records (USGS DDS-6; Denver GNULEX).
Probably does not extend much west of Kerber Creek in San Luis basin; its eastern limit is unknown. Does not possess uniform characteristics which suggests it may be the result of a multiple intrusion. Intrudes Bonanza and Hayden Peak latites. Mapped (geologic map) in east-central part of district. Is of Tertiary age.
Source: GNU records (USGS DDS-6; Denver GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
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