ERUPTIONS OF LAVA FROM THE LOWER LEVELS.
The Mauna Loa flows may be classified by the altitudes at which the discharges take place. First, those from the upper part of the dome, as those of 1843, 1852, 1855, 188o, 1889, and 1899, starting from 9,000 to ii,000 feet above the sea. They are strongly char acterized by a hydrostatic connection with the central pit at Mo kuaweoweo. The lava comes from the extreme depth under the ocean to the caldera, and after two or three days' stay at the sum mit it breaks out quietly on the side of the mountain, and may flow to the sea level in the course of several months. The other class, as represented by the flows of 1868, 1887, and 1907, shows first the same supply of lava at the summit, but breaks out low down, 3,000 or 6,000 feet above the sea, with violent earthquakes, those lowest down being the most frightful, and the lava issues tumultuously through long fissures. I can now add quite a num ber to the list of those that have issued from the lower level. They were prehistoric, so that it is impossible to connect them with manifestations in Mokuaweoweo.
In this class I will include several undefined aa eruptions east of Pahala. The first poses on the Government map as having been erupted in 1823, and is quite near Kilauea. As there rep resented, I think it is made up of three eruptions. The first, pre historic, 9,30o feet above the sea, near Puu Ulaula, well shown on E. D. Baldwin's unpublished survey. This probably was of the first class, originating high up. The second part must have been of the kind appearing at the surface low down, starting near the line between the Mauna Loa and Kilauea areas, at an elevation of more than 3,00o feet. A macadamized road now crosses it diagonally for as much as six miles, and it is certainly of prehistoric age. It has moved southwest with very little fall.
The third part originated from Kilauea in 1823, and is probably the only area that came to the surface at that time. It was visited
by Rev. Mr. Ellis in 1823 and is described in his journal.
The second mention is that of one or more ancient flows between the Halfway House and Pahala. Some of them cover the yellow ash beds, others are much older, or at least they had their day before the deposit of ash. Some of the recent exposures show a beautifully smooth pahoehoe, which when protected by an earthy covering really recall, by their freshness and smoothness, glaciated surfaces in more northern climes. Mr. Mann, one of the lunas at Hilea, told me he had seen five different lava flows belonging to this later period to the east of Pahala. They have a thickness of twenty-eight feet. This is in the vicinity of the mud flow of 1868.
Thirdly, extensive aa flows, which have originated in the de pressed area of Mohokea east of Puu Enuhe.
The fourth eruption is aa from between Puu Enuhe and Ma kanao.
The fifth eruption is made up of at least three aa flows and the later pahoehoe between Hilea and Honuapo.
In the sixth area there are some undetermined factors. Un doubtedly there were discharges on the Kahuku promontory be tween Honuapo and the 1868 flow, but we are sure of those of 1868, 1887 and 1907, which have been fully described. Farther north I observed from the steamer half a dozen of these short flows, of very modern aspect, before reaching Cape Honumalo. Here commences the steeper slopes of the Kona district for a distance of sixty miles. Much of the way the i,000 foot contour is only a mile back from the shore, and it rises nearly as rapidly to 3,00o and 4,00o feet. I observed fresh black lava flows at Hoopaloa, Naupoopoo, and Kailua. It seems clear, therefore, that there have been many eruptions from the lower levels of the Mauna Loa dome on the south and southwest sides. Whether any or all of them had direct connection with Mokuaweoweo, like those of 1868 and 1887, cannot be proved ; but their situation warrants a belief in their similarity.