Pg. G2 (fig. 1), G4 (table 1), G6 (fig. 2), G10-11 (table 2), G23 (fig. 3), G27-G31, pl. 1. Eckler Mountain Member, basal member of Wanapum Basalt of Yakima basalt subgroup [informal] of Columbia River Basalt Group. Name applied to flows between underlying Grande Ronde Basalt (new) and overlying Frenchman Springs Member of Wanapum. Thickness 20 to 25 m at type locality. Divided into 3 distinct informal flows (ascending): basalt of Robinette Mountain, basalt of Dodge, and basalt of Shumaker Creek; all have normal magnetic polarity (citing McKee and others [abs.], 1977, GSA Abs. with Prog., v. 9, no. 4, p. 463-464). Age is middle Miocene.
Type locality (see fig. 1, loc. 40 and pl. 1, fig. D): on south and southeast side of Eckler Mountain (misspelled Echler Mountain on Pullman 1- x 2-degree sheet), about 17 km southeast of Dayton, Columbia Co., WA, in the north half of sec. 26 and 27, T. 9 N., R. 40 E., Eckler Mountain quadrangle. This is the only known area in which flows of both the Dodge and Robinette Mountain chemical types occur in the same section. Two sites in the type locality where a Dodge-type flow overlies a Robinette Mountain flow are: (1) roadcut and cliff below road, in NW/4 NW/4 NE/4 sec. 26, T. 9 N., R. 40 E.; and (2) roadcut and cliff below road along the border of the SW/4 NE/4 and SE/4 NW/4 sec. 27, T. 9 N., R. 40 E.
[Yakima basalt subgroup considered informal and should not be capitalized. "Subgroup" not recognized as a formal stratigraphic rank term (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). Columbia River Basalt Group adopted by the ID, OR, and WA Geol. Surveys, and the USGS.]

Source: Publication; US geologic names lexicon (USGS Bull. 1564, p. 53); Changes in stratigraphic nomenclature, 1979 (USGS Bull. 1502-A, p. A24).