Lower and Middle Permian formations between Confusion Range, Millard Co., Utah, and Dry Mountain, White Pine Co., Nevada, have many distinct facies, but all pre-Kaibab Permian rocks may be referred to five formations. The stratigraphic succession at Illipah Gorge comprises Reipe Spring limestone, Reipetown sandstone, Pequop formation, and Loray formation. In the Confusion Range, Butte Mountains, and Ely area, Pequop and Loray formations are generally recognizable, but no distinctive boundary for mapping purposes can be recognized. In these areas, the Arcturus formation is used to designate the entire section between Reipetown sandstone and Kaibab limestone. Reipe Spring limestone is rather uniform in its physical characteristics, although it becomes somewhat arenaceous at Dry Mountain and silty in the Butte Mountains. A limestone-rich facies near Divide Spring, and mudstone rich facies at Dry Mountain represent the Reipetown sandstone. The lower Pequop formation consists of interbedded calcarenite and sandstone at Illipah Gorge, but at Dry Mountain an almost entirely mudstone facies is present. In the Ely area and Confusion Range this member is represented by interbedded limestones and sandstones of the lower Arcturus formation. Massive, crinoidal, and fusulinid-rich limestones of the upper Pequop formation at Moorman Ranch are represented in the Ely area by interbedded thin limestones and sandstones of the middle Arcturus formation. The upper Arcturus formation in the Ely area, Butte Mountains, and Confusion Range comprises thin interbedded red and yello sandstones and dark gray limestones similar to those of the Loray formation in the northeast part of the Illipah Quadrangle.

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