First use; intent to name not stated. Only exposure is in an area south of Cowboy Creek and east of Horse Hill [Mountain], secs 16 and 17, T31S, R17W, Walnut Wells quad, Hidalgo Co, NM in Pedregosa basin. Geologic map. Consists of heterogeneous rhyolitic pyroclastic rocks of tuff, agglomerate, and tuff breccia. Breccia is white to red with minor amounts of broken quartz and feldspar crystals; contains many foreign, angular, 1/2 to 3/4 in fragments. Matrix is cryptocrystalline. Thickness varies from 0-150 ft. Probably overlies Timberlake Fanglomerate (new); unconformably overlain by Bluff Creek Formation (new) and Young Ranch Tuff (new). Appears to be a thin remnant of early Tertiary volcanism. It probably inclined gently to the south and was mostly eroded before the deposition of younger volcanic rocks.

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