120 NATURAL HISTORY OP HAWAII. 



Hitchcock and others to wai-rant the conclusion that deposits of the Tertiary, 

 perhaps the Eocene period, form the foundation on Avhich the volcanic mass of 

 the original island of Kaala was formed. These eruptive deposits began to be 

 laid down under water, but in time the cone of Kaala built itself above the 

 ocean perhaps three thousand feet higher than the tallest peak of the Waianae 

 Range as we know it today. In reality the range is but the remains of a great 

 dome, more or less symmetrical, that at first arose above the waters. By the 

 erosive action of copious rains l)niiii;h1 then as now from over the sea, it was 

 deeply eaten away on all sides until its ancient form was very nearly effaced 

 During this period it slowly accumulated a stock of plants and animals from 

 other regions, partly from other islands near and far and jiartly from the distant 

 continents about the ocean. 



Subsequently the island which may be called Koolau, only twenty miles to 

 the north, was developed by a succession of eruptions, much as Kaala had develop- 

 ed before it, until its lavas and the soil eroded from them banked up several hun- 

 dred feet about the foot of the older adjacent island-mountain, uniting the two 

 islands into one and forming the plain of Wahiawa. It is asserted that Koolau 

 extended farther northeast than at present and that the active center of the 

 crater must have been beyond the foot of the Pali. 



As soon as conditions became favorable, limestone beuan to form as coral 

 reefs, probably fii'st about the oMcr island and hiter about tluMii both. It has 

 continued to be formed to the pres'/nt day thnnmli the various chemical, physical 

 and biologic agencies. Artesian well boriuus'" and other sources of in- 

 formation have revealed data to prove that <luring this innnensely long period 

 the surface of the island stood much higher than at present. 



The Pali crater and a doubtful crater near the head of Xuuanu Va'ley 

 give evidence of periodic activity during this time, such as the eruption of 

 the cellular or viscular lava, the formation of olivine laccoliths, and the intrusion 

 of dikes of solid basalt that filled in fissures in the older mass. The last evidence 

 of activity at the Pali ajipears in the form of an eruption of ash, clinkei's and 

 lava. 



About this time Kapuai and Makakilo craters in the Laeloa region at the 

 east end. of the Waianae Range, and perhaps one or more of the Tantalus 

 craters, were formed. Then came the ejection of some of the lavas met with 

 in the sinking of artesian wells and the forination of certain of the Laeloa 

 craters, also those at Kaimuki, Mauumai, and perhaps Rocky Hill, though Dr. 

 Bishop places the eruption of the solid basalt which comi)letely blocked the 

 mouth of Slanoa Valley at a nuii'h eai-liei- jiei'iod; but as its lower end extends a 



