THE CHANGES IN THE PIT.
Returning to Kilauea, Dr. Hillebrand states that on the 18th and Igth of April, the crater was entirely devoid of liquid lava. Large segments of the walls had fallen in on the west and eastern sides. The heat was considerable in the pit of Halemaumau, too great for the hand to hear. This pit was more than five hun dred feet deep. More than two-thirds of the old floor of Kilauea has caved in and sunk from one hundred to three hundred feet below the level of the remaining floor, the submergence having been most prominent in the western half. There was a depres sion from Halemaumau northwesterly, when a cliff three hundred feet high loomed through the mist. Surmounting this, Dr. Hillebrand found himself at the brink of a fearful chasm several hundred feet deep, and about half a mile long from south to north. Very hot air rose from it. Changes in the floor were taking place constantly.
Mr. Coan thus describes the same area as seen in August : "The central area of the great crater had subsided about three hundred feet, forming a new 'Black Ledge' of unequal width all around the crater. In some parts the central depression left the ledge a perpendicular or beetling wall with a serrated line, but in most parts the center sagged away gently, forming a large con cave basin with an angle of twenty to seventy degrees. The sur face of this concave was once the crowning or convex portion of the crater, where ferns and ohelo bushes had been growing for nearly twenty years. The superincumbent plateau has been de pressed so quietly that the surface is very little disturbed, and the ferns and ohelo bushes are still growing in the basin three hundred feet below their position on the first of April. Some parts, however, of this great area have been covered with fresh lava, and some ferns have been killed by heat and gases.
"From the Black Ledge I passed down and across this depres sion (about a mile) and then up the ascent on the other side for half a mile to the rim of Halemaumau. This is all changed; it has gone down some five hundred feet below the highest point on the Black Ledge, and about two hundred feet below the depres sion in the basin above mentioned. The walls have fallen on all sides, and the pit resembles a vast funnel, half a mile in dameter at the top and about 1,5oo feet across the bottom. There are two places where visitors can descend into this great pit, with some difficulty and risk. Much of the time, this pit is filled with smoke and sulphurous gases, with little visible fire ; occasionally, however, detonations and fiery demonstrations occur in this awful pit."
By comparing maps and notes it is possible to outline the area and dimensions of the lower pit created by the breakdown of April 2-5. More than two-thirds of the floor had collapsed, coin ciding approximately with the canals of Lyman, the ridges of Brigham, and later with the depression mapped by Lydgate in: 1874, an area of 8,000 feet long, 6,000 feet wide in the north eastern portion, narrowing to 3,00o feet at Halemaumau. The depth was greatest at the southern end, six hundred feet, half as much in the middle with sloping walls. The comparison of the basin to a heavy pie crust, "fallen in at the middle, leaving a part of the circumference bent down but clinging at the outside of the dish," well describes its appearance. Compared with the break down of 1840 it will be seen that the lava removed must have been about the same. The black ledge had increased somewhat in altitude between the two dates, at least fifty, perhaps one hun dred, feet. The task now set before the volcano for the next eighteen years, 1868-1886, is first to rebuild the mound of Hale maumau to a level with the black ledge, and then the filling of the basin so as to cover the entire floor.
It is stated by Mr. Nordhoff that just before the earthquake of April 2d, streams of lava oozed out through the crevices in the depressed area between Kilauea and Kilauea iki. The evidence of a lava flow is afforded by the adherence of lava to the trees, perhaps fifteen feet above the original surface. These were visible in 1886, and a photographic representation of the trees thus en crusted is presented in Plate 32. These incrustations may have been only a few clots thrown out from the opening.
The line of the fissure near Kilauea iki runs N. 6o° W. by compass in 1905. Between one and two hundred feet above the floor is a wide fissure lined with clinker or scoria, very fresh, of both bright red and black colors, the same material constituting the driblet cones. From this fissure there was a discharge of a considerable stream of ordinary as and pahoehoe down to the lowest level through the forest. It is easy to distinguish between the flows of 1832 and i868 by the presence of some vegetation on the earlier discharge. The specimens of clinkers are very much like those seen in the rent at Kahuku which came out at the same time, except that the latter contain a considerable green olivine.