The marginal moraines on the Hayden glacier are formed of fragments of brown and gray sandstone and black shale of all sizes and shapes. It is clear that this débris was gathered by the cliffs bordering the glacier on either side. The medial moraine which first appears at the surface just above the rapids is of a different character, and tells that the higher peaks of Mount Cook are composed, in part at least, of a different material from {111} the spurs projecting from it. The medial moraine looks black from a distance, but, on traversing it, it was found to be composed mainly of dark-green gabbro and serpentine. The débris is scattered over the surface in a belt several rods wide; but it is not deep, as the ice can almost everywhere be seen between the stones. Where the fragments of rock are most widely separated, there are fine illustrations of the manner in which small, dark stones absorb the heat of the sun and melt the ice beneath more rapidly than the surrounding surface, sinking into the ice so as to form little wells, several inches deep, filled with clear water. Larger stones, which are not warmed through during a day's sunshine, protect the ice beneath while the adjacent surface is melted, and consequently become elevated on pillars or pedestals of ice. The stones thus elevated are frequently large, and form tables which are nearly always inclined southward. In other instances the ice over large areas, especially along the center of the medial moraine, was covered with cones of fine, angular fragments from a few inches to three or four feet in height. These were not really piles of gravel, as they seemed, but consisted of cones of ice, sheeted over with thin layers of small stones. The secret of their formation, long since discovered on the glaciers of Switzerland, is that the gravel is first concentrated in a hole in the ice and, as the general surface melts away, acts like a large stone and protects the ice beneath. It is raised on a pedestal, but the gravel at the borders continually rolls down the sides and a conical form is the result. Where we crossed the Hayden glacier it is only about a mile broad in a direct line; but to traverse it by the circuitous route rendered necessary by the character of its surface required about three hours of hard tramping, even when unincumbered with packs. From the center of the glacier a magnificent view may be obtained of the snow-covered domes of Mount Cook, from which rugged mountain ridges stretch southward like great arms and enclose the white snow-field from which the glacier flows. At an elevation of 2,500 feet the icy portion disappears beneath the névé on which not a trace of débris is visible. All the higher portions of the mountains are white as snow can make them, except where the pinnacles and precipices are too steep to retain a covering.