Named for its limited occurrence near Young Ranch, sec 5, T31S, R17W, Walnut Wells quad, Hidalgo Co, NM in Pedregosa basin. Geologic map. Unconformably overlies Cedar Hill Andesite (new) west of ranch, and U-Bar Formation and Timberlake Fanglomerate (new) south of ranch. On northern flank of Horse Hill [Mountain], sec 8, T31S, R17W, unit is overlain with apparent disconformity by Gillespie Tuff (new). Basal beds west of ranch consist of sandstone and limestone deposited in a lake. Sandstone consists of angular grains derived from breakdown of a crystalline tuff. Limestone has fine wavy laminae. These sedimentary lake beds disconformably overlie Cedar Hill Andesite (new). Remainder of unit is a columnar-jointed, flat-lying deposit at least 100 ft thick. Consists of welded tuff, tuff, and tuff-breccia, and is of quartz latite composition. Rock is cream to light grayish brown with flat green lenses. More indurated toward base with compaction characteristics. Upper part is friable and lacks compaction features. Is probably equivalent to Bluff Creek Formation (new), which it resembles in lithology and stratigraphic position. Is Tertiary in age.

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