AFRO-INDIAN REGIONS. 



461 



mense furnace of the molten lake, with all its intensity of heat, fails 

 to produce the slightest impression on the atmosphere around the brink 

 of the Crater : and after standing on an area heated a few feet below 

 almost to whiteness ; placing my hand upon rock, that a foot beneath 

 set on firewood pressed against it; the conclusion was unavoidable, 

 that the Earth's internal heat has had nothing to do with climate. 



Lava from the Great Crater is to be found only in the immediate 

 neighborhood of the crescent-like Crevice of formation and eruption : 

 and notwithstanding the above-described lava-stream, and similar ones 

 that have preceded it, the amount remaining on the island is compara- 

 tively trifling. The Great Crater itself is in Mauna Roa lava : and 

 with the line of pit-craters, shows that the Mauna Roa lava-streams 

 are piled upon each other more than a thousand feet vertically. The 

 Great Crater is in fact only a lateral almost basal crater of Mauna Roa ; 

 and the whole may be regarded as one volcano. 



The ascent of Mauna Roa. To return now to the morning when 

 Captain Wilkes' party, leaving the Great Crater, were proceeding nearly 

 due West, towards the summit of Mauna Roa. The path continued 

 distinct for some miles, over a surface evidently a little declining; 

 where the lava in flowing had risen several feet above its level in un- 

 dulations or knolls. Taller shrubs soon began to make their appear- 

 ance, four to eight feet high, and many of them clustered : as the 

 DodotKxa, more abundant than I have seen it elsewhere ; the Osteo- 

 meles, also unusually abundant; and of more generally-distributed 

 shrubs, a Metrosideros ; gen. Epacrid., two to three feet high ; a Vac- 

 cinium ; and others. Extensive patches of soil were observed to be in 

 large proportion bare; even where decomposed into fine dust, and 

 seeming well-adapted to support a vegetable growth. 



At length the ground began perceptibly to rise ; the ascent com- 

 mencing with a dry grassy savanna, two to three miles wide, and 

 almost like a belt ; extending, say from the elevation of thirty-eight 

 hundred feet to that of forty-four hundred. Within this savanna, the 

 rock was seldom exposed ; the surface being entirely covered with a 

 matted sward of (je7i. Poac. ; a remarkable grass, two to three feet 

 high, chiefly leafy at the summit and very rarely in flower; its hard 

 consistence, and the want of water, seeming to preclude pasturage. 

 In crossing, I met with but three other kinds of plants : in places 

 where the growth was somewhat thinner, an occasional stem of a Pteris 

 resembling P. aquilina, or of the twining GoccuJus? Fermndianus ; 



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