This unnamed sedimentary and volcanic sequence was first described by Ketner (1975) in the northern Adobe Range where it extends from Coal Canyon to Long Canyon.

This sedimentary and volcanic unit contains Permian and Triassic rocks which span post-Wolfcampian through Lower Triassic time (Coats, 1985). A low-angle fault separates the Permian and overlying Triassic rocks. The two sequences have been mapped separately in the northern Adobe Range by Ketner and Ross (1983).

The Permian-Triassic sedimentary and volcanic sequence originally mapped within the northern Adobe Range is composed of somewhat unique facies that are difficult to correlate with other stratigraphic units. Although originally mapped together as a Permian-Triassic sequence (Ketner, 1970, 1975), recent work in the northern Adobe Range has shown that two sequences are present; a low-angle fault separates Permian lithologies from overlying Triassic rocks (Ketner and Ross, 1983).

Ketner and Ross (1983) have retained map units that include unnamed lower, middle and upper Permian units and an unnamed Lower Triassic unit of shale and limestone. In this report the units have been combined and retained a single sequence both for convenience on the map, and because of a lack of a more rigorous correlation with already named Permian and Triassic formations. Coats (1985) has also retained this unit and describes it as a single sedimentary and volcanic sequence.

The Early Triassic rocks make up most of this sequence and are mainly thin-bedded and platy, silty, dark gray to chocolate brown weathering limestone, and olive to gray-green shale. The limestones show graded beds, sole marks, slumps and olistrostromes, which according to Ketner and Ross (1983), were derived from the Permian Gerster Formation. Greenstone sills and flows up to 20 feet thick are in some cases traceable for over a mile, and locally contain rounded boulders of Paleozoic sedimentary rocks (Ketner and Ross, 1983).

The Permian portion of the section is composed of various proportions of sandstone, conglomerate, limestone, dolomite, phosphatic siltstone and phosphatic chert. Ketner and Ross (1983) divided the Permian portion of the section into Lower, Middle and Upper Permian units. The Lower Member is composed of chert-pebble conglomerate, chert-quartz sandstone, cherty limestone, dolomite and spiculitic chert. This is overlain by the Middle Permian Member that is composed of cross-bedded phosphatic siltstone. The Upper Permian Member is slightly phosphatic quartz siltstone and sandstone with small pelecypods (Ketner and Ross, 1983).

The Permian-Triassic sedimentary and volcanic sequence in the northern Adobe Range is estimated to be more than 2,000 feet thick (Ketner, 1975b; Coats, 1985).

The Permian-Triassic sedimentary and volcanic sequence is only exposed in the northern Adobe Range.

Ketner and Ross (1983) suggest that the Triassic portion of this section represents slope and basin deposits, or a deeper water facies of the Triassic rocks exposed farther to the east in northeastern Elko County. The Permian phosphatic limestone, siltstone and sandstone represent relatively shallow marine near-shelf sedimentation with clastic influx from surrounding low-lying islands.