OF THE HAWAIIAN ISLANDS. 435 



task. From the reports of natives, we learn that there is much very fertile land on the 

 plateaus which might be rendered accessible by roads cut through the thicket. Should the 

 islands ever be annexed to the United States, American enterprise, with American capital, 

 will doubtless utilize these now savage and deserted tracts. 



Oahu. — As on Kauai, the lava has issued from two centres, but the vents were not 

 clustered around two points, thus forming a symmetrical peak, but are arranged in two lines 

 parallel to the general trend of the group; resulting in two mountain chains. 



At some period of its history Oahu must have suffered from vast forces tending to rend 

 its mountains, which however acted in a quiet way as when Mauna Loa is broken to admit 

 the passage of lava. The result has been a detachment of a portion of the northern slope 

 of the eastern or Konahuanui ridge, and this fragment has wholly disappeared. I cannot with 

 Prof. Dana consider the missing portion so large that the remaining mountain is but a small 

 part of the original mass. He had never seen the line of craters extending through fifteen 

 miles along the centre of the Konahuanui Range. Kaneohe Point was perhaps the im- 

 mediate result of the great rupture ; the engulfed portion has made shoal water to the 

 distance of a mile and a half from the shore, and the lavas from the crack piled up the 

 craters of Kaneohe and the various islands along the coast. 



Sinking Oahu two hundred feet makes a very great change in its topography, and seems 

 to explain many puzzles. There are then two islands; the cliffs almost perpendicular on the 

 Koolau side are washed by the waves that drive against them on the windward side ; the 

 rounded cones of Koko are under the waves, and Leahi is an island half a mile from shore ; 

 the currents and winds strike its tufa walls, and it is slowly washed away on the windward 

 side. On the south of the island of Konahuanui is a series of deep bays from Palolo valley 

 to beyond Kalihi, on the west. Puawalna is on the shore, while Aliapaakai is almost sub- 

 merged, its material being swept away by the currents to form the extensive shoal of Laeloa. 

 The Kaala mountains form an island similar in most respects to the Konahuanui, but being 

 on the lee side are less exposed to marine erosion. 



What are the indications that this picture of Oahu is outlined from fact ? The rounded 

 cones of Koko are perhaps a more striking proof than even the raised coral reef wdiich ex- 

 tends nearly around the island. That tufa cones are sometimes thrown up on land with a 

 rounded summit I do not deny ; but a crater is always present in such cases. Even the 

 winds and meteoric influences generally do not obliterate it ; submarine currents alone do 

 that when the cone is growing, or at least before it has become cemented by meteoric in- 

 fluences. The plain between the two ridges is however the most conclusive proof. Fine 

 natural sections are exhibited in the bed of the several streams which traverse it in very 

 winding courses, and there we see broad beds of alluvial deposit of uniform thickness, which 

 were undoubtedly formed beneath the water. Above these however are irregular bands of 

 varying thickness extending to the surface, evidently subaerial in their formation. Indeed, 

 every severe storm adds to their number, when the mountain torrents invade the plain and 

 tear away from one portion to pile upon another, or break down from the mountains by 

 other than their usual routes, carrying with them earth and rocks. The upper level of the 

 submarine beds is from a hundred to a hundred and seventy-five feet above the sea. Frag- 

 ments of coral are found in them, and a careful search would probably reveal shells 



The erosion of the sea-walls of Puawaina and Leahi, the former now some distance 



