Looking up at the layers of Glacier Park. You can also see expired beargrass. Most of this is the Grinnell Formation: Because of their dominantly red color, the shaly argillites which comprise the bulk of this formation are the most conspicuous rocks in the park. They lie immediately on top of the Appekunny and although their thickness varies considerably it is greater than 3,000 feet in several localities Oxidation of the Grinnell formation probably took place while the mud was accumulating and during those periods when it was exposed to the atmosphere. At such times also the mud dried and cracked, the marks of which are so prominent on the surfaces of the layers today (Ranger Bob pointed this out to us in one area right along the trail).

Next above the Grinnell is a thick limestone formation which, because of its weathered buff color, stands out in sharp contrast to the red beds upon which it rests. It is the greatest cliff-maker in the park and in several places its entire thickness of 4,000 feet may be exposed in a single nearly vertical cliff. Since it is younger than the three preceding formations, it is confined mainly to the higher elevations.