346 



W. T. BRIGHAM ON THE VOLCANIC PHENOMENA 



but the dip is towards the sea in every part examined, and sometimes exceeds 10°. Dana 

 noticed, in a height of one hundred and fifty feet, ten layers each from ten to thirty feet 

 thick. 1 



South of Nawiliwili, and separating the district of Puna from that of Kona, is a ridge of 

 similar appearance, but much greater height (2290 feet by triangulation). The side towards 

 the north is steep and generally inaccessible, except where two breaks occur, the western 

 one affording an excellent roadway. So far as examined the dip was towards the south, 

 about 10°-12°, and the seeming dip on the northern side was due to the successive de- 

 posits of wash from the mountains. 



The region between Mauna Kalalea on the north, Mauna Nounou and Kapu on the east, 

 and the Koloa Ridge on the south, forms a semicircle of about seven miles radius, elevated 

 about two hundred feet above the sea, and is mostly rolling land covered with grass and 

 occasional groves of pandanus or koa (Acacia koa). Near Koloa at the south-eastern end of the 

 island, is a very interesting region where the volcanic fires have left their latest traces. 

 Over nearly ten square miles the lavas are fresh and but little decomposed, although the 

 cluster of craters from which it probably came occupies but a tenth of that space. From 

 the Koloa ridge to the sea the pahoehoe, or smooth lava, extends, in some places covered with 

 large blocks lying loosely together, or with a red earth which nourishes a few argemone, 

 sida. and indigo bushes. This barren surface is uneven, being in many places bulged up in 

 immense bubbles some of which have fallen in, leaving caverns, one of which near the shore 

 is paved with the ancient coral reef. 



Dana's description of these craters is very complete, and leaves 

 little to be added. He says: 2 " The old crater (C) has a steep 

 and ragged summit, consisting of dark-brown lavas and scoriae 

 The cone stands about one hundred and fifty feet above the plain. 

 The bare sides are smooth until near the summit, where the lava 

 breaks out in columns, so rude and jagged as scarcely to justify 

 the term, yet appearing columnar from below. It forms a narrow 

 wall, or crest, broken by numerous rents, and is mostly wanting 

 on the east-south-east and wes<>north-west sides. The crater is 

 about one hundred and fifty yards wide at top, and has a depth 

 of thirty or forty yards. The surface within is smooth, and con- 

 sists of red earth like the lower slopes of the interior. The 

 lava of the crest owes its roughness, in part, to a thin laminated 

 structure and numerous vertical fractures. The laminae are from half an inch to two 

 inches thick, and although not easily separated, they stand out prominent over the worn 

 or decomposed surface. The rock has been rendered very irregular from disintegration, 

 and, at top, the columns are sometimes unevenly tapering. Besides these sources of its 

 rough features, the walls within are covered with lava in twisted shapes, forming patches 

 plastered on the surface, or hanging in stalactites. The rock of the crest is very cellular, 

 and much of it is scoriaceous. 



To seaward from the old crater, the observer looks down upon a low, broad elevation (D), 

 with a shallow crater at top. Its smooth surface, covered with scanty vegetation, at first 

 suggested that the lava had not flowed from it. But the crater proved to be half filled 



l Loc. cit. p. 270. 



2 Loc. cit. p. 273. 



