96 J. D. Dana — Geological History of Oahu. 



that mud-making warm waters were concerned in the deposi- 

 tion ; and its being of brown, in place of red, color, is probable 

 evidence that the temperature of the water was below 200° F. 



Diamond Hill, fig. 1, makes the prominent cape east of 

 the city ; its bold southern brow has a height of 761 feet 

 above the sea at its base. It is, like Punchbowl, a fine example 

 of the typical tufa-cone in its broad and shallow, saucer-shaped 

 crater, with the stratification parallel to the bottom of the sau- 

 cer and to the original outer slope. These slopes have become 

 deeply trenched, as the view shows, by descending waters ; and 

 since 1840, the southern brow has lost something of its bold- 

 ness. Two other cones stand in a line to the north of it, the 

 first, a place of lava outflow. The three vents appear to be sit- 

 uated on a single line of fracture. 



The Koko Head tufa-cones are situated at the east extremity 

 of the island. The view (fig. 3) was taken from the east- 

 ward at sea The larger or more northern of the two cones is 

 much denuded inside and out. The other low cone, situated 

 on the Point, is worn to its center by the sea, and has thereby 

 been made to exhibit to the passing vessel (as it goes from ot 

 toward Honolulu) the dip of its tufa beds inward and outward, 

 and thereby the true structure of such a cone. 



Artesian borings on Oahu afford some facts bearing on the 

 history of Diamond Head and Punchbowl. The borings 

 were made by Mr. J. A. McCandless of Honolulu, and records 

 of a number of them have been received, from him through 

 Prof. W. D. Alexander. 



The following section is from James Campbell's well, at the 

 west foot of Diamond Head, not far from the sea-level. 



Thickness. Depth. 



Gravel and beach sand 50 feet 



Tufa like that of Diamond Head 270 320 feet 



Hard coral rook, like marble 505 825 



Dark brown clay 75 900 



Washed gravel. 25 925 



Deep red clay 95 1020 



Soft white coral 28 1048 



Soapstone-like rock . 20 1068 



Brown clay and broken coral 110 1178 



Hard blue lava 45 1223 



Black and red clay 28 1251 



Brown lava 249 1500 



The well went down 1178 feet before reaching the solid lava 

 of .the bottom. In its upper part it passed through 270 feet 

 of tufa, indicating that the tufa-cone extended below the sea- 

 level to this depth, and therefore had a total height of over 

 1000 feet. Below the tufa, between the 320-foot and 825-foot 



