Lying on top of the Altyn are 3,000 or more feet of prevailing greenish
shales and argillites[2] comprising the Appekunny formation. Slabs of
these rocks, because of their great hardness, have been used as
flagstones in the walks at the Many Glacier Ranger Station and adjacent
Park Service residential area. Mud cracks and ripple marks are common.
The formation is prominent on the side of Singleshot Mountain near the
St. Mary entrance to the park, and everywhere immediately overlying the
lighter-hued Altyn along the east edge of the Lewis Range where,
especially when seen from a distance, it appears to have a purplish
color. It also outcrops along the western base of the Livingstone Range
(Figure 3D), but such exposures are as a rule obscured by a cover of
dense forest. Accessible outcrops can readily be examined along
Going-to-the-Sun Highway for several miles east of Sun Point and near
McDonald Falls, and also along the lower part of the Grinnell Glacier
trail.