•134 W. T. BRIGHAM ON THE VOLCANIC PHENOMENA 



centre Waialeale, and numerous breaks, so extensive as to divide the chain into several 

 apparently distinct ridges, have the same direction. 



The lavas did not reach the surface in a single vent over each axis, as on Halcakala, 

 Mauna Loa, Kilauea or Kea, but were distributed in a number of craters, several of which 

 were simultaneously active as on Hualalai and Kohala. 



The solid, unstratified axis of Waialeale is a cone with a greater diameter in proportion 

 to its height than that of either Kaala, Konahuanui or Eeka, indicating either an intenser 

 heat or a longer period of activity. From the greater horizontal extent of this solid core 

 Kauai retains more moisture on the surface and has thus become more decomposed through 

 the superficial strata that mark the successive overflows of lava ; and its compact summit, 

 almost constantly bathed in clouds, collects and retains enough water to form swamps and 

 springs, the sources of large and constant streams whose rapidly descending currents are 

 still enlarging the ravines and valleys they have hollowed out on all sides of the mountain 

 Vegetation has been promoted, and in turn has decomposed the rock, forming earth which 

 will retain water, so that now, from the base to the summit, Waialeale is clothed with ver- 

 dure, and its middle slopes are covered with large and ancient forests. In taking denudation 

 as an index of age, regard must of course be had to the material acted upon. °The greater 

 the height, and the steeper the slope, the more transporting and wearing power will the 

 water have; the more compact the rock the more water will be retained to form streams • 

 and if the rock in the upper regions is easily detached in blocks, a grinding and cutting 

 machine is supplied of which water is only the motive power. As the hard boulders cu° 

 out the pot-holes in the bed of a stream, so the rough, freshly broken masses of hard basalt 

 from which the rounded boulders are formed, cut and tear away the softer strata which have 

 been in succession the surface of the mountain, and even cut deeply into the very core 

 which is composed of their own material. The rock of the summit of Waialeale is a very 

 hard clinkstone, which is brought down in the numerous torrents, and is found in rounded 

 boulders blocking the bed in the mile or so of nearly level course near the shore. The 

 erosion is almost visible from day to day, clearly from year to year. On Mauna L6a 

 the rock is porous, the core is not proportionally thick, and the rains form no single 

 stream, and of course there are no water-worn valleys. 



The beach sandstones near Hanalei are buried from eighteen to twenty-four inches be- 

 neath the surface by the deposit of the river which extends over many square miles, but 

 this is the only case on the island where anything like a delta is formed by fluvial deposits 

 Even during the storms, when the streams are swollen and the bed is worn away to a con- 

 siderable extent, the waters are not remarkably muddy, and they become quite clear as soon 

 as the freshet begins to subside. 



The evidences of elevation on Kauai are by no means so satisfactory as on Oahu The so- 

 called raised reef near Koloa, I am satisfied, is only a consolidated dune of coral sand; and 

 all the sandstones on the shores may easily have been formed in their present positions 

 The fact that the water near the shores is becoming shallower, only shows that the deposits 

 washed down from the mountains are not removed by the waves as fast as they form. I did 

 not see any marks of subsidence. 



The interior elevated regions of Kauai will doubtless reveal to the future explorer many 

 interesting geological facts ; no other island of the group promises so much, but like northern 

 Hawaii the rank vegetation and difficult ridges and ravines make the exploration no easy 



