THE LATEST SUBMERGENCE AND REELEVATION.
It would seem as if there must be evidence of the submergence of Oahu after the accumulation of the talus-breccia to the depth of two hundred and fifty feet. The relation of the deposit to the talus-breccia may be seen at the quarry, where at the altitude of about forty feet there is a red earth with many marine remains directly overlying the talus-breccia. Beside the mollusca, there are corals and remains of fish. This is the only place where the relation of these shells to the talus-breccia is clear. What seems to be the same material rises to two hundred feet at the north base of Diamond Head and is also seen at the lower levels. I do not recognize anything like a shoreline, but the marine shells are frequent. Near Doctor Wood's summer house, one hundred feet above the ocean, at Kupikipikio, are Cvpreas and Turbo, both shells and opercula. The surface is strewn with rough blocks. The shells are seen when the lava fragments are thrown to one side in a very red earth, the residuary remains of the Kaimuki lava.
A study of the fields at the Waialua plantation gives related results. The cultivated tracts seem like aqueous and residuary deposits, utilized to the height of about three hundred feet. I
found shells and opercula of the marine gastropods in numerous localities and Melanias up to two hundred and fifty feet altitude.
I had no opportunity to see these remains in any excavations ; they all lie on the surface of the ground.
I think a little search will prove the existence of scacliffs toward Kaena point, to the west of Waialua. Looking from the rail road train, there seem to be three wave-cut terraces in the basalt, the highest one at about the level of the shells picked up from the sugar fields. The excavations may not be strongly marked, as it is presumed that time of the submergence was brief ; but it seems evident that there must have been a very recent de pression of the island to the depth of two hundred and fifty feet, very likely in the Pliocene. If so, the age of the smaller land shells in the talus-breccia will be established. As has been re marked, it would seem necessary for as long a period as that to have elapsed to account for the development of the Achatinellidae.