The upper beds which form some of the higher pinnacles consist of layers of snow-white gypsum and red compact sandstone, from the thickness of paper to a few feet, alternating in an endless round.
The rock has a most curiously painted appearance.

At the pass of the Peuquenes in this formation, where however a black rock like clay-slate, without many laminae, occurring with a pale limestone, has replaced the red sandstone, I found abundant impressions of shells.

The elevation must be between 12 and 13,000 feet.

A shell which I believe is the Gryphaea is the most abundant--an Ostrea, Turratella, Ammonites, small bivalves, Terebratulae ( ?).

Perhaps some good conchologist (6/1.