Abstract

Most of the marine metasedimentary rocks of northeastern Stevens County are tentatively correlated with three of the Cambrian formations established by Park and Cannon (1943) in the Metaline quadrangle, immediately to the east. Of the established Cambrian succession, the formations of northeastern Stevens County include the Metaline limestone, Maitlen phyllite, and the upper half of the Gypsy quartzite. Contacts are gradational. Fossils are scarce, and most of the correlations are based on lithology.

The Metaline limestone appears to be over 6000 feet thick and underlies the Ordovician Ledbetter slate. The brachiopods, Nisusia sp. and Acrotreta sp., were found near the middle of the formation on Gladstone Mountain. They indicate, according to Bridge, an early Middle Cambrian age, as do the trilobites found at a lower horizon in the Metaline quadrangle. The upper third of the formation is fine-grained, locally cherty calcite and dolomite marbles. The central third is white sugary dolomite marble with many beds of darker dolomite. Near shear zones much tremolite has formed. The basal third consists of alternations of gray limestone and phyllite beds.

The Maitlen phyllite, over 3700 feet thick, includes black, gray, and green phyllites and a quartzite unit.

The Gypsy quartzite includes 2500 feet of arkosic and micaceous quartzite with a few marble beds.

The Cedar Creek argillite, over 2800 feet thick, is probably correlative with the Maitlen phyllite and the Red Top limestone with the Metaline limestone.

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