FOSSIL TREES IN LAVA.
In the definition of fossils it is expressly stated that the im pressions made by organisms upon other substances must he in cluded as well as where portions of the animated object had been preserved. Thus a footmark proves the former existence of an animal as truly as a bone. In Hawaii we have the impressions made by the stumps of trees upon the encircling lava, where the heated streams flowed through a forest. One would think that the trees would be entirely destroyed, but as a forest fire leaves behind the stubs of trees unconsumed and standing like senti nels, so the lava streams have been unable to burn the green wood of the interior. The simplest case is where a stream has pushed its way rapidly through the trees. All the brushwood, branches, bark and leaves are consumed, but the heart of fhe tree refuses to yield, and the trunks are coated with lava. In other cases the branches have caught bits of lava that have been sprayed upon them. Such an example is illustrated in Plate 32 where the lava has adhered to the trees twenty feet above ground. This was in the 1868 eruption at Kilauea iki and these evidences of the flow were visible there for more than twenty years.
The next stage is where the lava has completely enveloped the trees and solidified around the trunks. In the case of the material falling as ashes the stumps will be enclosed in a similar manner and be better preserved, as seen at Moanalua, on Oahu, by the side of the railroad (Plate 6, Fig. 2, Geology of Oahu). These were compared with the casts of Carboniferous trees found at the Joggins in Nova Scotia, which were surrounded by thick strata of sand. After the decay of the trees deep holes took their places into which amphibians fell and were entombed by a later deposit of sand, and the trunks were replaced by solid sandstone. Usually after the decay of the trees only cylindrical holes are left, upon whose walls may be seen the imprint of charcoal and occa sionally some of the charred wood. Rarely new forms or other plants take root and grow up in these holes. In traversing the
country away from any trail one needs to take care to avoid these holes for fear of accidents.
Near Kilauea, on the Shipman ranch, is a large koa grove in which these tree moulds are abundant, some of them five and six feet in diameter. Smaller ones may represent the locations of so many coconut trees. The lava encircling the ancient trees prob ably came from Kilauea, and may be twenty feet thick.
In the district of Puna may be seen hundreds of lava tree stumps standing erect in the fields as pillars, often fifteen feet high. It cannot be said that these pillars originated from the filling up of the moulds, and then the lava removed or that they represent basalt encircling stumps. A better theory is that of Mr. Rufus Lyman, as stated by Rev. Mr. Westervelt. The lava moves among the trees encircling them to its full thickness. Many will burn but the larger ones will chill the lava so that it hardens around them, drying the outer rim. This will then burn, leav ing a small space around the tree, which will receive the still plastic lava forced by the pressure of the liquid and make a sheath around the stub. More burning and more pressure will add to the thickness of this sheath, so long as the conditions suit able for the growth prevail. Sometimes two or three stumps are connected by the lava growth. Plate 25 shows one of these tree moulds, much expanded at the top and supporting vegetation.
The Hawaiian legends relate that these tree stumps represented chiefs in the early days, who had been beguiled by Pele to race with her upon the holua sleds, like the contest described earlier of Kahawali. Pele became indignant when worsted in the race and poured forth floods of lava to overwhelm her opponents. Those who were caught were left standing as pillars all over the plain—and many of the people were destroyed at the same time. Kamapuaa, Kamukahi and Papalauwahi were chiefs who were turned into tree-stumps : and the date of their existence would be the time of a pre-historic eruption from Kilauea.