166 PICKERING. — LUNAR AND HAWAIIAN PHYSICAL FEATURES COMPARED. 
Clavius. The photograph was taken in 1903 by Mr. C W. Baldwin, and was 
forwarded to me through the kindness of Professor W. D. Alexander. 
One of the most interesting craters that we visited was Kilauea Iki, or little 
Kilauea. It is situated about a mile from the Volcano House. The floor is level, 
one-quarter of a mile in diameter and 750 feet below the rim. The walls are very 
steep, but can be descended in certain places with care. Numerous small craterlets 
are scattered irregularly over the floor. The most complete of these is shown in 
Figure 19. Its height was 15 feet, and the diameter of the rim, which was composed 
of lava of a somewhat ropy appearance, 25 feet. A stream of lava had poured from 
the summit, but did not get far beyond the rim. There may have been as many as 
fifty rudimentary craterlets scattered over the floor, in all stages of growth, from 
a hardly noticeable elevation to the complete craterlet shown in the figure. 
The process of construction was clearly shown, and was probably identical with 
that which produced Halemaumau, and Kilauea itself in the first place. In Figure 20 
the top of one of the other craterlets is represented in the foreground. It was taken 
near at hand from the summit of the first one, and its development is clearly incom- 
plete. The surface of the crater floor of Kilauea Iki seems to have solidified into 
a layer six to ten inches in depth and distinct from the portions below it, much as in 
the case of the sixth crater, Figure 8. A liquid core forced up from below raised 
this surface layer locally, and shattered it into separate pieces like cakes of ice. 
This core in the case of some of the smaller craterlets was sometimes only two or 
three feet in diameter, and could be seen beneath the shattered surface. In one 
instance its summit seemed to have an almost globular form, five feet in diameter. 
If the volcanic forces beneath these craterlets had been more intense, it is probable 
that the issuing lava would have completely destroyed them, forming a series of 
crater pits, into which the lava would have subsequently retreated. In the south- 
eastern part of the floor two such pits were found, perhaps 15 feet in depth by 
30 in diameter, down into which a stream of lava had poured, but had solidified 
without filling them up. One of these pits is shown in Figure 21. Figures 20 
and 19 therefore illustrate the earliest stages of formation of a lunar crater. No 
other example in Hawaii is known to the writer which shows as satisfactorily as this 
the irregular distribution of craterlets over a crater floor. 
A low ridge due to compression, caused by the sinking of the convex surface 
crosses the eastern end of the crater floor. Similar ridges are seen on some of the lunar 
maria, notably on Serenitatis, Figure 17. Two short, clearly marked ridges project 
onto the southern side of the floor of Kilauea Iki, caused by lava streams which had 
