OF THE HAWAIIAN ISLANDS. 



361 



baked it hard and given it a deep red color ; at the same time its structure has been 

 rendered beautifully prismatic, the penta-hexagonal 

 prisms being about an inch in diameter and two or 

 three long. The lava above is in a thin sheet, and 

 probably cooled rapidly, as no effects of heat are vis- 

 ible half a foot from the surface. 



Fig. 18. Section of a lava stream at Leahi. 



There are two other craters nearly in a line with Le&hi, but low, and mostly composed of 

 lava ; probably they were the vents which supplied the lava covering this region. All the 

 country in the neighborhood is dry and barren. Smooth beds of lava are covered with blocks 

 of similar rock of all sizes from one to one hundred cubic feet, indicating- that a lava How 

 had underrun and burst up a previous stream. Where a river from Palolo Valley has broken 

 through the deposit, three or four strata are visible near the base of the Konahuanui range 

 — their probable source. The coral reef is much cracked and tilted, and is of great thick- 

 ness, some of the natural pits or caves being twenty or thirty feet deep with a coral bottom. 

 The upper surface is rough, and so colored by the ochre of the earth in the neighborhood, 

 as to lose all appearance of organic origin, and to closely resemble lava. 



Punch-bowl, or Fort Hill, is directly behind Honolulu, adjoining the west 



Puawaina Group. . . 



ridge of Manoa Valley, and blocking the entrance to Pauoa. It much resembles 

 Leahi, but is much smaller. Its brown tufa sides have an arid aspect, except during April 



Fig. 19. Puawaina from Punahoii ( -s — East). 



and May, when the rains water the scanty crop of grass which covers the whole hill with an 

 evanescent mantle of green. The summit is about five hundred feet above the sea, 1 and as 

 its substance is harder and more closely bound by the roots of the grass and shrubs on its 

 surface, it has suffered less than Leahi, still an examination of its southern edge shows that 

 less than one half of its pristine size remains. In Dixon's " Voyage Around the World," a 

 view of the cone is given, presenting high peaks ; this was in 1786, and the natives declare 

 that " many ages since, it had such a form." 



The crater at the top is very shallow and covered with green sward. Its diameter is 

 about six hundred yards, and it is of the usual oval form. The tufa is beautifully laminated, 

 and well exhibits the double dip of about thirty degrees on each side of the rim. Lime 

 encrusts the tufa on the south side, and seams of the same white substance occur in such 

 abundance as to give the outer slope in many places a whitewashed appearance. 



Near the little battery on the summit, is a rough pile of cellular lava and scoria? which 



MEMOIRS BOST. 60C. NAT. I7IST. 



1 Found by President Alexander to be 460 feet. 

 Vol. I. Pt. 3. 92 



