20 C. H. HITCHCOCK — GEOLOGY OF OAHU 



range, corresponding to a longer cliff or pali,as it is called in Hawaiian, 

 on the cast side of Koolau. Plate 2 illustrates the flutings or valleys 

 of erosion made by existing streams on the side of the Kaala pali. 



Koolau Range 



The mountains in the larger eastern district are arranged natural l}' 

 by their drainage into two parts, so obvious as to have received distinct 

 Hawaiian names. The more northwesterly part is Koolauloa, about 15 

 miles long, reaching to the peak named Kaumakua. The drainage on 

 the interior side is entirely to the north. The other section, called Koo- 

 laupoko, is 22 miles long, with its interior drainage directed into the 

 Pearl Harbor system, except the southeastern part, where the streams 

 flow directly into the sea. 



The extreme northwesterly point of Koolauloa is Kakuku, where are 

 interesting limestones to be described later. The valleys become more 

 pronounced to the southwest, and at Waimeabay is a considerable canyon 

 fully 400 feet deep, with many branches high up. Three or four large 

 canyons converge and discharge in two adjacent channels at Waialua, and 

 they drain also the northeast slopes of Kaala. The longest of the Waialua 

 series of canyons commences on the north flank of Kaumakua and is 16 

 miles long. The slope may be from 3 to 5 degrees to the north from the 

 axis of the range, making an inclined plateau which has been cut into 

 several ravines. The greater part of this plateau has rarely been visited. 

 It is noticeable that the western slope of Koolauloa is continuous to the 

 very base of Kaala on the Waialua side. The same is true of the southern 

 slope toward Ewa, with its canyons. The largest of these gorges passes 

 through the Oahu sugar plantation. Only one altitude is given for any 

 of the Koolauloa peaks, which is 2,360 feet at the summit, a short distance 

 north of Kaumakua, and the descent from here to the limestone cliff at 

 Kahuku is gradual. From Kahuku along the northeast shore the ground 

 is low and flat to beyond the village of Laie. Off the shore are several 

 small limestone islands. There are as many as six large valleys with 

 steep sides between Laie and the end of the Koolauloa region. These 

 are Kaipapau, Haaula, Kaluwaa, Punaluu, Kahana, and others. Kalu- 

 waa presents vertical walls rising a thousand feet in pinnacles, a cascade 

 at the end, and the " canoe,'' a smooth cylindrical shaft 30 or 40 feet in 

 diameter, 300 feet high, and resembling a canoe standing on end. There 

 is another longer channel a mile beyond, diminishing in rise upward at 

 the top of the cliff, a thousand feet high. Both these grooves are the 

 work of streams. 



