436 



W. T. BRIGHAM ON THE VOLCANIC PHENOMENA 



from the shore, can hardly be due to pluvial influences alone ; the material of Puawalna is 

 too evenly spread over the elevated reef which forms the foundation of the city of Honolulu. 

 I am much inclined to the belief that Oahu has been elevated nearly two hundred feet since 

 the coast craters were formed. 



Whether this elevation was gradual and long continued, or spasmodic and extensive, is not 

 easily determined, for the steps in the ancient elevated reef which would seem to indicate 

 the latter, may have been formed by subsequent earthquakes, and there are no distinct 

 terraces or ancient beaches to be traced around the island. Molokai is the only other island 

 which bears evident signs of elevation, and on examining these two islands, it seemed as if the 

 axis of Konahuanui was not vertical but inclined towards the north-north-west ; or that the 

 island of Oahu had been raised at the south-eastern end nearest Molokai much higher than at 

 the opposite side. On Molokai the appearance was still stronger, but owing to the removal of 

 nearly the whole of the windward slope on both islands it is perhaps impossible to determine 

 by measurement whether this inclination of the mountain axis really exists. Certainly one 

 shore appears to have been elevated more than the other. Possibly the eruption which 

 cracked Konahuanui and opened the Nuuanu and Manoa craters, formed Leahi and the other 



coast craters, and inaugurated the elevation 

 of the island. 



The lineal arrangement of craters has 

 not been before noticed on Oahu ; indeed, 

 few explorers have had the time required 

 to scale the sharp ridges and penetrate the 

 dense jungle of the valleys. Manoa and 

 Nuuanu have already been referred to as 

 craters, and their shape will readily be seen 

 from the sketch-map (Fig. 6), where B rep- 

 resents Nuuanu, D Manoa. Precisely sim- 

 ilar to these are the valleys west of Kalihi, 

 and at Punaluu a complete cone crater is 

 found. The nature of the Konahuanui 

 Range precludes the possibility of a longi- 

 tudinal path, and the explorer must ascend 

 every lateral ridge, a toilsome journey. 



On the Kaala Ridge many of the an- 

 cient craters are now marshes or ponds, 

 and the same is true of Konahuanui to a 

 less extent. 

 Earthquake throes usually vibrate from 



Map of the Valleys near Honolulu. . .. . , _ 



. , , the mountains to the sea on all sides 01 



A, small cone in Nuuanu ; B, circus of Nuuanu Valley ; C, smooth corneal peak ; 

 D, Manoa Valley; E, stream from Pauoa Valley ; F, stream from Maklki Valley. OilllU, pei'liapS indicating a Solid axis OVer 



a, fissure not yet wholly cut off from internal commotions. 



Molokai. — This island was formed much in the same way as Oahu, by the union of the 

 overflows of two linear vents. The western part never attained the dimensions of a moun- 

 tain, and bears many tokens of having been wholly formed beneath the sea, while the 



