Named as member of Carefree Formation (new). Named for Grapevine Rd. Type locality on southern bank of White Eagle Wash, south of Grapevine Rd, 0.25 mi south of Grapevine Springs, Cave Creek quad, northern Maricopa Co., central AZ. Occurs in eastern and south-central parts of Carefree basin covering approx 12.5 sq mi; largest, thickest, most widespread member. Primarily characterized by its high (75%) granite-grus (decomposed granite) content. Described as tan to gray, horizontally bedded, poorly to moderately sorted, moderately consolidated, granitic fanglomerate, with locally interbedded quartz sand lenses. Commonly contains many thin calcium carbonate layers within sand and gravel, and rock fragments from nearby basalt, meta-argillite, or rhyolite exposures. Well log and cross section measurements show 1000 feet maximum thickness. To east, unconformably overlies or is in fault contact with Middle Proterozoic (1400 Ma) Camelback Granite (new); in southeastern and south-central part of study area, conformably overlies Miocene tuff and basalt; in central part, overlain by late Miocene and early Pliocene Galloway, Naked Girl Canyon, and Sombrero Members of Carefree Formation (all new) and by remnants of Pleistocene Schoolhouse Glacis Alluvium and Pleistocene Desert Mountain Glacis Alluvium (both new), or by Pleistocene Horny Toad Terrace deposits (new) and Holocene Vermeersch Alluvium (new). Laterally grades into Sombrero and Naked Girl Canyon Members or is in steeply dipping depositional or fault contact with Naked Girl Canyon Member. Age is late Miocene and early Pliocene based on constraining minimum radiometric date of <13.4 Ma of White Eagle Mine Formation (new). Report includes geologic map and cross section, and stratigraphic nomenclature table.

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