A ridge crest west of Epidote Peak exposes a third geologic unit composed of highly sheared unidfferentiated marble and metasedimentary rocks.

[3][4][5] The Greenlee Formation consists of beds of fine-grained, micaceous quartzite and argillite that form the eastern slopes of Epidote Peak on the west side of Shackleton Glacier.

At the base of the slopes of Epdiote Peak that are adjacent ot Shackleton Glacier, the micaceous quartzites and argillites are intruded by granitic migmatitic gneisses.

It consists of a series of highly metamorphosed and sheared basaltic lava flows interbedded with graywackes and felsitic volcanic rocks.

Within the ridge crest west of Epidote Peak, the Taylor Formation consists of highly sheared silicic volcanic rocks, typically porphyritic felsite.

[3][4][5] At the western ends of ridges associated with Epidote Peak, thick beds of white, coarsely crystalline marble are exposed.

The relationship of the marble beds to each other and the Taylor and Greenlee formations is completely obscured by intense cataclasis and shearing of them and enclosing strata.