A year later Mr. Green visited the source of this flow and found a small cone, which was the mouth of a chimney, eighteen to twenty-eight feet wide and of unknown great depth. The stream below was compared to a hollow pie—the contents had disappeared leaving only a broken down crust.
On the morning of Feb. Toth the Oahu party visited the be of the flow for the last time. The lava rushed out of the subterranean passage with great velocity, at a white heat and as thin as water. Masses of lava were thrown up from ten to fifty feet into the air which cooled in falling. Three hours later the pool had become a fountain playing to the height of thirty feet. Plate 16B. Pieces of the lava ascended as much as one hundred and eighty feet and cooled as they fell. Gases were escaping at two other points. The crater was ten feet high. This jet had been discharging for fifteen days.
Concerning the stream below, Alexander writes: "It was for tunately a clear day on the mountain, and a strong wind was blowing from the southwest, so that we traveled for three or four hours along the very brink of the stream without inconvenience. It had worn for itself a deep, well defined channel, so that there was no danger of any sudden change in its course. The canal in which it ran varied from twenty to fifty feet in width and was ten to fifteen feet deep. But the stream was in reality much wider than this, for the banks on either side were undermined to a considerable distance. Often we met with openings in the crust, through which we could see the rushing torrent a few feet, or even inches, below our feet. * * * We saw actual waves and actual spray of liquid lava. As its surges rolled back from the enclosing walls of rock, they curled over and broke like combers on the reef. Its forms, however, were bolder and more picturesque than those of running water, on account of its being a heavier and more tenacious fluid. There was besides an end less variety in its forms. Now passed a cascade, then a whirl pool, then a smooth majestic river, then a series of rapids, toss ing their waves like a stormy sea ; now rolling into lurid caverns, the roofs of which were hung with red-hot stalactites, and then under arches which it had thrown over itself in sportive triumph. The safety with which it could be approached was a matter of astonishment to us all. r'"' "As the descent became more gradual (eight or ten miles down) the torrent changed its color, first to rose color, then to a dark blood red; its surface began to gather a grayish scum, and large drifting masses became frequent. It now began to separate with numerous branches, and it became more unsafe to follow the cen tral stream, as changes were constantly taking place, and our retreat was liable to be cut off at any moment. * * * "We had been particularly anxious to see how clinkers are formed, and our curiosity was now gratified. The difference be tween pahoehoe, or smooth lava, and aa, or clinkers, seems to be due more to a difference in their mode of cooling than to any other cause. The streams which form the pahoehoe are com paratively shallow, in a state of complete fusion, and cool sud denly in a mass. The aa streams, on the other hand, are deep, sometimes moving along in a mass twenty feet high, with solid walls ; they are less fluid, being full of solid points, or centers of cooling, as they may be called, and advance very slowly. That is, in cooling, the aa stream grains like sugar. At a distance it looks like an immense mass of half red-hot cinders and slag from a foundry, rolling along over and over itself, impelled by an irre sistible power from behind and beneath. That power is the liquid
stream, almost concealed by the pile of cinders which have been formed from itself in cooling." Under date of June 22d, Professor Haskell writes, after a visit to the source of the '59 flow, that the stream was much smaller than in February; it is entirely subterranean for twenty five or thirty miles, though a few holes exist where the lava can be seen. He climbed to Mokuaweoweo where no per ceptible action was noted.
Mr. W. L. Green observed the entrance of the lava into the sea, both in January and several months later: "The red hot lava was quietly tumbling into the sea over a low ledge, per haps six or eight feet high, and five hundred to six hundred feet long. The lava did not seem to be quite so liquid, or of such a bright color as it did when it ran out of openings in the side walls of the aa stream upon the mountain some months before. It ran more like porridge in great flattened spheroids, which were sometimes partially united together, and sometimes al most separate. The cooling was to be expected after its long journey down the mountain. There was no steam to be seen escaping from the lava, and it was not until after each sphe roidal mass had disappeared for a second or two under water that puffs of steam came to the surface. The general effect, however, was an apparent steady rise of steam along the whole line. It was a cataract of molten stone." Mr, Green remarked that this tendency to form spheroids in the molten state might have some connection with the origin of basaltic columns, as well as to weathered spheroidal masses seen in ancient lava streams, developed through decomposition and exhibiting concentric coats. He allows that there was nothing like compression: the great flattened spheroids rolled quietly over into the sea, causing a slight commotion in the water. The boat was pulled very near the boiling mass, and was set rapidly outward, because of the rise of water from below. The origin of the concentric structure is, however, quite likely to be explained by the production of these spheroids.
In 1864 Professor Brigham walked over more than eight miles of the upper part of the 1859 flow in an ascent of Mauna Loa, The surface was black, shining and quite brittle. In some places the lava had flowed up hill. Bubbles of great size were common, some of them broken in. Immense beds of as with nearly vertical sides and extremely rough fragments crossed the flow in various directions, being always level on the top.
Mokuaweoweo varied scarcely from the conditions described by Wilkes. It was visited August 5th, and is alluded to later.
According to the record book, Messrs. J. L. \Visley, Charles Hall and M. Worman ascended to Mokuaweoweo in 1865. They went up on the north side past the source of the 1859 flow. The summit pit was said to be shaped like the figure 8. They descended to the bottom, finding two steam holes upon the west side. There was a line of openings or gashes up the mountain along the line of the 1859 flow, as well as pumice and sand at the point of outburst.
In 1865 light was seen at the summit of Mauna Loa, De cember 3oth, and continued for four months, with variations in its intensity. No one ascended to the summit and there is no record of any outflow of lava anyhere upon the side of the mountain.