1^ A' _^ 



1 



i 



t « 



.£1.^* 



On the Recent Condition of Kilanea. 77 



I 



X • At the Ulterior marsrin of what has been described as the Black 



I 



%^ 



ledge, especially on the northeast and east, our attention was 

 _, particularly attracted by a continuous ridge more than a mile in 

 length, consisting of angular blocks of compact lava, resembling 

 the debris at the foot of a range of trap or basalt. This ridge rose 

 on its outer or eastern face often to the height of fifty or one hun- 

 dred feet, especially towards the south where it approached the 

 Great lake ; and generally it left a space, or " canal," as it has been 

 called, between it and the ledge several rods in width, and in some 

 ♦ ^ places forty or fifty feet in depth. This was apparently what had 



once constituted a talus, or accumulation of debris on the floor of 

 the crater at the foot of the nearly perpendicular precipice of the 

 Black ledge, at a time when the floor was three or four hundred 

 feet below its level at the date of our visit. That floor, with its 

 margm of debris having been subsequently elevated, partly by 

 upheaving forces from beneath, and partly by successive overflow- 

 ings from the Great lake and other active vents formerly exist- 

 in|| at length rose higher than the precipice at the foot of which 

 It was accumulated, and presented to view the rocky ridge Ave 

 nave been describing — a phenomenon that seems inexplicable on 

 any other hypothesfs than that of the bodily upheaving of the 

 inner floor, of the crater. The fact of such elevation, is further 

 evident from the appearance of these ridges on their inner or 

 ^vestern slope. This side was broken and precipitous like the 

 other, but of a much inferior altitude. Indeed, the altitude grad- 

 ually diminished towards the southern portion of the ridge, till in 

 the Vicinity of the Great lake, instead of a ridge it became sim- 

 ply a precipitous bluff facing the east, from the top of which 

 spread out an uneven plateau occupying the whole central por- 

 tion of the crater north of the lake, and elevated more than a 

 hundred feet above the Black ledge. This wall was too steep 

 and high to be scaled by our party, but the plateau just mentioned 

 j^vas subsequently visited by the writer, and at its southeastern 



ifnit so precipitous was the descent, that stones hurled from the 

 / nand cleared the foot of the bluff", and occupied nearly three sec- 



onds m falling — which would give for the perpendicular eleva- 

 tion the amount that has just been stated. 



A hns the entire portion of the crater within the black ledge 

 appears to have been filled up, or elevated, on an average more 

 "lan 40t) feet between 1840 and 1846; and from the testimony 

 ot subsequent observers, it would seem that the process of eleva- 

 "on, especially in the neighborhood of the Great lake, has been 

 going on with greater or less etficiency to the present time. 



Ihe "canal" spoken of, or the space between the inner mar- 

 s'" of the old Black ledge, and the outer margin of the central 

 portion of the crater, was so named from the fact that formerly, 



'nen u was 200 feet deep or more, niolten lava had been ob- 



1 



« 



ttb. 



Tfe 





