The lake lowered only apportionately to the slowing black outflow on the south floor, which was short-lived. This was the beginning of a splitting open of the main Kilauea Mountain flank southwest and outside the crater which continued for months. Another adventure, and an important one, happened with the outflooding of lava in the Kau Desert, where terrace upon terrace of pahoehoe lava was building up. This finally became a hill over the rift, two miles long and 200 feet high, which we called Mauna Iki, or little Mauna Loa. The exploration, day after day, of the extending quiet lava outwelling along this rift made it necessary to find new trails from the Pahala roadway and across the desert to the lengthening hillock. Following the new Mauna Iki trail, Mr. Finch noticed that the ancient ash beds, two or three feet thick, had surfaces as hard as Portland cement. And on one of these he, like Robinson Crusoe, found the print of a naked foot, made when the old ash was a mud. On the trail across these old surfaces many more hardened, ancient footprints were found, of men, women, children, and pigs headed both up and down the mountain. [Illustration: _18. Isabel and Tom Jaggar in woods on Kilauea Volcano on their return from viewing 1923 eruption in Napau Crater_] [Illustration: _19. Lava lake, fountains, and crags, March 20, 1921_] [Illustration: _20. Footprints in ash west of Mauna Iki, said to have been made by Keoua’s army during Halemaumau eruption of 1790_] These prints recalled the story of Keoua’s army when there was a big explosive eruption of Halemaumau in 1790 and the mud rains of the period were from ash which had been baked by the volcanic fires. If roasted and moistened, the chemical composition of powdered basalt is that of weak cement, and these surfaces were in hollows which had resisted erosion wash for 130 years. Part of the slopes closer to Halemaumau had been eroded bare, but they also showed footprints. Later the trail was followed up the mountain close to Kilauea Crater and down toward Pahala, and the ash of 1790 was found to be made up of pisolites, or fossil raindrops, in many places. Evidently the eruption had been accompanied by torrential thunder storms, and the natives had walked through the deposits of mud, which had in a century been dried by the sun into a resistant surface. These fossil footprints were to become one of the attractions of a tourist trail in the National Park.