114 NATURAL HISTORY OF HAWAII. 



and find their outlet to tlie ocean thi'ough the yreat Pearl Loehs already men- 

 tioned. 



The windward side shows i)lainly the full foree of dreneliing' rains-' and 

 the euttinii- winds, for the seaward surfaces are everywhere deeply eroded and 

 the disintegrated lava removed, leaving a series of amphitheaters, narrow 

 promontory-like outlying ridges and clitfs that mark the more resistant cores of 

 the solid rock. 



The erosion of the Kaala dome is not so easily understood since the greater 

 excavations are on the west side, while the slopes which are to windward, that 

 is towards the Koolau range, are more gradual. But as the "Waianae Moun- 

 tains are conceded to be much older than the opposite range it is presumed that 

 the conditions which exist now are much modified from those that were in effect 

 when the Waianae Range was first eaten down. 



Smaller Bas.\ltic Craters and Tuff-Cones. 



While the main ranges already discussed are of first importance in the 

 topography of the island, the later volcanic manifestations, especially of the series 

 of basaltic craters and tuff-cones that mark the close of volcanic activity on 

 Oahu, form striking objects in the general contour of the island. 



The tuff-cones are the most numerous and conspicuous, several being in view 

 from Honolulu. Of these Diamond Head, or Leahi, the famous landmark often 

 spoken of as the sphynx of the Pacific, is the most noticeable. As the traveler 

 approaches the island for the first time Diamond Head with its imposing, rugged 

 outline is sure to attract attention ; often, too, it is the last parting glimpse of 

 Diamond Head from the distance, as the voyager leaves the island behind, that 

 brings the full realization to mind of all that it typifies of the life in a tropic 

 land that has so fascinated him that, wander where he will, Oahu's shores seem 

 always to call him back again. 



Diamond Head. 



Diamontl Head rises in bold relief from the shore-line ])eyond Waikiki, to 

 the height of 761 feet. While its sharp outline may seem to suggest to some the 

 appropriate and accepted popular name by which the point is known far and 

 wide, the name was, in fact, derived from the excitement created through the 

 discovery by sailors at an early day of small calcite crystals "^ that they thought 

 to be diamonds. 



This crater mountain looks from the outside to l)e solid rock, but in 

 reality it is a great hollow oval tuff-cone, 4,000 by 3,300 feet in its diameters, 

 with its elongation in the direction of the trade winds. Owing to the e.i'ecta 

 being carried by tlie jircvailing winds when the crater was in eruption the 

 southwest side of tliis and of similar cones on the island is considerably higher 

 than is the opposite side. Inside the crater the walls slope gently to the center, 

 where, near the eastern wall, during the wet season, there is, or at least there 



= The annual rainfall al tlic Pali usually exceeds 150 inrhe.s. "Still to t>e liad for the Katliering. 



