DIAMOND HEAD 45 



" Las lost something of its boldness " by erosion. W. T. Brigham says 

 on page 20 of his " Notes : " 



" In the winter of 1864, during a severe rain, when 36 inches of water fell in a 

 week, a deposit of mud 2 feet in depth was formed over the inner basin, and the 

 degradation of the exterior was still more extensive. The southwest end, which 

 is the highest point, was formerly quite accessible, but can now [1867] only be 

 scaled by ladders or ropes." 



It was quite easily climbed in 1883 and is at the present time, as is evi- 

 denced by the fact of its ascent by thousands of soldiers in their brief 

 sojourns at Honolulu en route to and from Manila. Mr Brigham thinks 

 the summit is now (1899) 25 feet lower than it was when he first explored 

 it, more than 30 years previous. 



The relations of Diamond head to Kaimuki, the next volcanic cone 

 inland, are very clear. The basalt of Kaimuki clearly overlies the tuff 

 in the notch between the two craters. Its superior position is apparent 

 for several rods, and the tuff has evidently been affected by the heat of 

 the basalt. The relations are still better seen at the promontory east of 

 Diamond head called Kupikipikio, which owes its existence to the thick 

 basaltic flow which covered the tuff over many acres of extent. The 

 tuff is capped by fine black ashes from 9 to 10 feet thick, thought to have 

 come from Diamond head, because in the spot nearest that summit the}' 

 slope away from it. No signs of this ash have been recognized on the 

 leeward side, probably because of the prevalence of very low ground and 

 of the ocean. The greatest distance of carriage on Kupikipikio is not 

 quite three-quarters of a mile from the eastern rim of Diamond head. 

 The upper part of the ash has been weathered to a reddish brown color 

 and covered by the basalt ; so the section is very clearly tuff at the base, 

 ashes both unaltered and weathered, covered by basalt. 



It may be well to describe here the interesting basaltic dike, perhaps 

 of later origin than the ash beds, as they seem at one place to have been 

 disturbed by its ejection. Quite near the last house on the seashore, 

 coming easterly from the lighthouse, is a fine exposure of a basaltic dike 

 from 3 to 6 feet wide, forming a cliff 25 feet high, exposed to the sea. 

 It is very nearly vertical, possibly inclined 80 degrees northeasterly. Its 

 course by compass is north 50 degrees west, running toward Diamond 

 head. Farther on, this dike has cut the coral reef for several hundred 

 feet. It stands apart by itself, the softer limestone having been eroded 

 by wave action, and it looks like the foundation wall of some building. 

 The outside of this exposed dike is compact, next its boundary walls, 

 and the inside is composed of spherical pieces of basalt, with concentric 

 structure inside. Petrographically it resembles the Kaimuki basalt. 



