Southeast of craggy Lyell, mountain climax and eastern outpost of the Yosemite National Park, the Muir Trail follows the extravagantly beautiful beginnings of the Middle Fork of the San Joaquin River through a region of myriad waters and snow-flecked mountains. Banner Peak, Ritter Mountain, Thousand Island Lake, Volcanic Ridge, Shadow Lake—national park scenery in its noblest expression, but not yet national park.
A score of miles from Lyell, the trail follows the river into a volcanic bottom from whose forest rises the splendid group of pentagonal basaltic columns which was made a national monument in 1911 under the title of the Devil's Postpile. Those who know the famous Giant's Causeway of the Irish coast will know it in kind, but not in beauty.
The enormous uplift which created the Sierra was accompanied on both its slopes by extensive volcanic eruptions, the remains of which are frequently visible to the traveller. The huge basaltic crystals of the Devil's Postpile were a product of this volcanic outpouring; they formed deep within the hot masses which poured over the region for miles around. Their upper ends have become exposed by the erosion of the ages by which the cinder soil and softer rock around them have been worn away.
The trail traveller comes suddenly upon this splendid group. It is elevated, as if it were the front of a small ridge, its posts standing on end, side by side, in close formation. Below it, covering the front of the ridge down to the line of the trail, is an enormous talus mass of broken pieces. The appropriateness of the name strikes one at the first glance. This is really a postpile, every post carefully hewn to pattern, all of nearly equal length. The talus heap below suggests that his Satanic Majesty was utilizing it also as a woodpile, and had sawn many of the posts into lengths to fit the furnaces which we have been taught that he keeps hot for the wicked.
Certainly it is a beautiful, interesting, and even an imposing spectacle. One also thinks of it as a gigantic organ, whose many hundred pipes rise many feet in air. Its lofty position, seen from the viewpoint of the trail, is one of dignity; it overlooks the pines and firs surrounding the clearing in which the observer stands. The trees on the higher level scarcely overtop it; in part, it is outlined against the sky.
"The Devil's Postpile," writes Professor Joseph N. LeConte, Muir's successor as the prophet of the Sierra, "is a wonderful cliff of columnar basalt, facing the river. The columns are quite perfect prisms, nearly vertical and fitted together like the cells of a honeycomb. Most of the prisms are pentagonal, though some are of four or six sides. The standing columns are about two feet in diameter and forty feet high. At the base of the cliff is an enormous basalt structure, but, wherever the bed-rock is exposed beneath the pumice covering, the same formation can be seen."
An error in the proclamation papers made the official title of this monument the Devil Postpile, and thus it must legally appear in all official documents.
The reservation also includes the Rainbow Fall of the San Juan River, one of the most beautiful waterfalls of the sub-Sierra region, besides soda springs and hot springs. This entire reservation was originally included in the Yosemite National Park, but was cut out by an unappreciative committee appointed to revise boundaries. It is to be hoped that Congress will soon restore it to its rightful status.