PICKERING. LUNAR AND HAWAIIAN PHYSICAL FEATURES COMPARKD. 16 
descended from the crater wall. They resemble similarly located formations found 
in the lunar crater Plato. In Clavius, Figure 16, similar ridges are seen projecting 
from the outer slopes of the two chief craterlets upon the northern and southern 
walls. Similar ridges, although much more complicated in structure on account 
of their numbers, have already been described in Bullialdus, Figure 5. 
Leaving the craterlets and ridges of Kilauea Iki, and proceeding along a defile 
towards Kilauea itself, three successive lava dams were reached, each of which had 
served to hold back a small lava lake. In construction they were similar to the 
circular one represented in Figure 12, except that they were straight, and merely 
stretched across the defile. The first lake measured 400 feet in length by 150 in 
breadth. The second dam rose eight feet above its surface, and three feet above 
that of the second lake. By the side of this lake a core of lava of the most brilliant 
colors — red, yellow, brown, and purple — had escaped from the ground, and from it 
a black lava stream had descended to the surface of Kilauea Iki, 200 feet below. 
A similar core but without the colors was seen at Huehue. Both these flows occurred 
during the last century. Both were small, and in neither case did a cone appear, 
the lava issuing directly from the ground. 
The fourth subdivision of the lava craters, described earlier as crater bowls, is 
illustrated in Hawaii by what is known as Aloi, or the Third Crater, near Kilauea. 
Other illustrations are found on the slopes of Hualalai. A crater near the summit, 
j, p. 171, was estimated at 800 feet in diameter by 200 in depth. The sloping walls 
were of lava, and the bottom of sand. The comparatively shelving outer walls 
probably did not exceed 100 feet in height. A portion of the interior of this crater 
is shown in Figure 22. A somewhat larger crater bowl with much steeper walls 
is found on the summit. With favorable definition such a crater would be readily 
seen upon the Moon, and could not be distinguished in any way from many others 
found there. 
The largest craters on Hualalai occurred near the summit, and shortly before 
reaching the top we crossed a lava field strongly resembling a small lunar marc, 
A far larger number of craters are found on this mountain than on any of the 
thers, more perhap 
the others combined. The three types, of cind 
cones, pits, and bowls, are each represented by numerous examples. One of the 
craters that we passed after leaving the summit, k, p. 171, had sloping walls and a flat 
floor with sand hills on the bottom. One of these was twenty feet in height. Near 
the base of the walls was an inner terrace extending all around the crater. Thi 
feature of a single, well marked, inner terrace is conspicuous in a considerable 
