MAUNA KEA.
Mauna Kea is the white mountain of Hawaii as indicated by the name. It is capped with snow for a longer time and more often than any other summit in the archipelago, because of its greater altitude, 13,825 feet. The snow prevails from November till March, and intermittently later in the year. I never saw snow of a more dazzling white than what fell in connection with thun der showers on July 23, 24, 25, 1905. The snow furnishes the material for the pond Waiau, one hundred and twenty-five feet long above 14,000 feet. This body of water is situated in the midst of an extinct crater. Ice forms in it even in the summer, the temperature falling as low as 13° F. in the middle of July.
Mauna Kea is a cone with a diameter of thirty miles, rather ellipsoidal, with a northwesterly trend, and a corrugated surface, whether seen from the north or south. See Plate 13. Mauna Loa differs from it by having a comparatively smooth surface. Being younger there has not been the opportunity to multiply cin der cones upon it. If the early history of Mauna Kea has been like that of Mauna Loa these cinder cones cover an ancient cal dera. There are many canyons about the base of Mauna Kea which are likewise criteria of a greater age.
Mauna Kea is ascended from the east and southwest sides, or from the coast and the sheep ranch Humuula in the col between Kea and Loa. The slope is usually as much as twelve degrees, but more upon the north side. Mauna Loa may show a slope of seven degrees where steepest, but only four degrees where the whole dome is kept in view.
There is a sort of plateau upon the higher part of Mauna Kea above the contour of 12,500 feet, with an area of from thirty-five to forty square miles. It is shown in Plate 12A, which is a copy of the map prepared by Prof. W. D. Alexander in 1892 when in the company of the party of Mr. E. D. Preston of the U. S, Coast and Geodetic Survey. Upon this plateau above the contour of 6,500 feet are scattered more than seventy-five cinder cones, mostly of a red color. Similar cones are scattered less numerously upon the flanks of the mountain. Towards the southwestern base some of the material is black, though red at the surface because of weathering. Some of it cannot be distinguished from the black
ash covering a large part of the city of Honolulu.
These cones correspond so closely with the related "terminal" craters at the heads of the flows upon Mauna Loa that I reproduce a sketch of a very fine one seen from the summit of Mauna Kea, Plate 12B, taken from Mr. Preston's report, U. S. G. & G. S., 1893, The observer stands upon the very summit of Mauna Kea, Ku kahaula, and looks southwesterly. In the foreground appear the rough blocks at the summit, one crater near by and two or three others in the distance, besides the one that is so prominent in front, and is taken as the representative of the others. It has the typical slope of the true cinder cone. Judging from the phenomena presented at the making of the corresponding cones upon Mauna Loa there was a stream of liquid lava either quietly welling up or rising as a column in the center. As this material fell to the ground about the orifice, it was divided into fragments known as cinders or lapili, and then still finer volcanic ash and dust, of which the impalpable part may be blown into the atmos phere and transported by the wind to great distances. The Mauna Kea summit cones are usually perfect ; those that appear elsewhere have one side worn down to permit the still liquid streams to flow away. Later this crevasse was enlarged by the action of subaerial water seeking a lower level.
The cone at the summit is covered by blocks of consolidated lava, including many bombs, some of them three or four feet long in shape like ornamental ear-pendants. Those that I ex amined had a nucleus of olivine enveloped by a white basaltic rock—much as if the darker silicates had been segregated into a central mass while the whiter feldspars aggregated them selves to the exterior. Observers who are not experts may be excused for calling this material granite; so much does it super ficially resemble that rock. The whole mass, before the green core and white exterior have been broken apart is properly a volcanic bomb.