Variations in the Lava of the 1959 Eruption in Kilauea Iki!

IN · RECENT YEARS the Hawaiian Islands have become of great importance in studies concerned with igneous petrogenic theory. This is partly because of the total absence in that region of sialic crust that might affect the formation of other rock types by its assimilation in rising magma. Partly, also, it is because of the extensive lateral and vertical exposure of successions of rocks, the structural and stratigraphic relationships of which are now well known. These conditions have attracted to the area workers from many parts of the world, and progress in knowledge of Hawaiian rocks has been rapid. The knowledge is, of course, the accumulation of the findings of many workers, starting with the visit of J. D. Dana to the islands in 1840, as a member of the U. S. Exploring Expedition. Outstanding among recent workers are Hisashi Kuno of Tokyo University, P. Niggli of the University of Zurich, C. E. Tilley of Cambridge University, H. S. Yoder of the Geophysical Laboratory of the Carnegie Institution of Washington , and H. A. Powers of the United States Geological Survey. During 1960 and 1961 two studies have largely confirmed, but also extended and somewhat modified, the previous petrogenic picture. In April, 1960, the junior author of this paper, on leave from the Tokyo Institute of Technology, commenced a series of chemical analyses of Hawaiian lavas at the University of Hawaii under a National Science Foundation grant to the senior author. At the end of March, 1961, approximately 150 new analyses, primarily of the hitherto largely neglected "primitive" lavas of the Hawaiian volcanoes, had been completed. These have helped fill important gaps in the basic knowledge of Hawaiian rocks. Study of them is continuing. During July, 1960, a core hole was drilled in the crust of the recently erupted lava pool in Kilauea Iki crater of Kilauea volcano, and pene-