358 W. T. BRIGHAM ON THE VOLCANIC PHENOMENA 



sides, seem beyond the power of a rude waterfall. A few rods beyond this is the present 

 waterfall, which has worn its way down from above until its waters gush out of a narrow 

 cleft, clear of the wall, into a dark pool below, which only the mid-day sun ever shines upon, 

 so close are the walls above it. There is no possibility of scaling the walls of the valley; 

 and to examine the gorge above, one must retrace his way to the shore and ascend the 

 ridges. There are two falls above this, one of them invisible but audible ; the other, some 

 three or four hundred feet high, may be seen from the shore some four miles distant. It 

 may be a matter of interest to some future traveller to trace the ancient conduits, and see 

 what has twice diverted the stream. 



At Laie the drift-sand has formed hills of sand-stone hard enough for building purposes. 

 These hills are thirty or forty feet high, much broken by earthquakes apparently, and worn 

 by the action of wind and rain, into grotesque honey-combed masses and ragged pinnacles. 

 From the white color of this stone it has often been mistaken for elevated coral reef. Near 

 Kahuku the sand-hills are of greater size and height, and much resemble an elevated beach. 

 The tracks of a plover, identical with the existing species, were discovered imbedded in the 

 sand-stone nearly a hundred feet above the sea. The stone splits readily into slabs, and is 

 white, hard, and of a coarse texture. The elevated reef near Kahuku, and all along the 

 north-west end of Oahu, is quite distinct and full of large caves. A light-colored rock in 

 rounded masses is sometimes met with at this end of the island. It is a light, porous gray- 

 stone, and always occurs beneath beds of red cellular lava. 



The Shore Craters of Oahu. — Although the main mountains of Oahu exhibit few craters or 

 cones in perfect condition, there are along the shores fine examples of tufa cones. These 

 occur in six groups: at Kaneohe, Koko, Leadii, Puawaina, Aliapaakai, and Laeloa. 



On the peninsula that forms the eastern side of Kaneohe Bay are four hills, 



° up ' three of which exhibit craters. Excepting these volcanic hills the surface is 



flat and formed of coral limestone elevated but a few feet above high-water level. The largest 



crater (A) is much broken down by the sea ; no lava stream has 

 been discovered. The next cone towards the land (B) is almost 

 wholly composed of a compact, black, heavy lava, which has 

 flowed out towards the sea, although now wholly hidden hy ac- 

 cumulating sand. The other two hills (C, D) are small, and made 

 up of lava similar to the last. A crater (F) some rods from shore 

 has not been examined ; it much resembles the island off Maka- 

 puu. At E is a low ridge nearly covered by sand, which appears 

 to be the remains of a crater nearly as large as A. Both C 

 and D have been much worn by the waves on the sea front, 

 Fig. 12. Plan of Kaneohe Craters, while they have been covered by sand towards the shore, a fact 

 that would render their identification difficult were it not for the description of Dana 

 written some twenty-five years ago. This erosion has taken place in spite of the pro- 

 tecting coral-reef which fringes this coast. Along the shore to the west are one or two 

 small islands of like origin, but much worn away by the sea which has obliterated all 

 traces of craters. 



