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



coral, 22 feet of white coral rock; 110 feet more of the coral 

 rock above the 260-foot level, and 65 feet of " tough clay and 

 coral " next above the 350-foot level. Further, beginning with 

 the 385-foot level, coral rock is continued to the TOO-foot level, 

 or for 315 feet, with the exception of 40 feet of clay divided 

 between three layers ; and this 315-foot layer of limestone ap- 

 pears to correspond to the 505-foot layer between 320 and 825 

 feet in the other section. The solid lava-stream of the bottom 

 of the well was reached at 730 feet. The amount of water 

 obtained proved that the lava-stream was one of those from 

 the mountain. It is overlaid by 2 feet of volcanic sand and 

 28 of tough clay, the sand serving to contain the water and the 

 clay to confine it, conditions suited to make the well a success. 



In these sections the intercalated beds of so-called " clay " 

 vary widely in position and thickness, and appear to be, in gen- 

 eral, local deposits from mountain streams, or tufa deposits 

 from one source or another. In another boring in Waikiki, a 

 bottom of solid lava was reached at 375 feet ; and in a third, 

 Goo Kim's well, at 475 feet. The former had an intercalated 

 lava-stream at a depth of 206 feet, and the other at 150 feet. 

 In Goo Kim's well, which was nearly a mile from the seashore, 

 there were 26 feet of coral rock above the 150-foot level, and 

 194 feet of coral rock above the 430-foot level but with two 

 intercalations of a 20-foot layer of " clay " in the stratum. 

 The facts as to the varying levels of the " clay " beds and the 

 intercalation of lava-streams show what accidents the living 

 species of the sea and its reefs were exposed to. They make 

 the existence of a continuous 505-foot stratum of coral lime- 

 stone underneath the tufa of Diamond Head the more re- 

 markable. 



The artesian wells made within the limits of the city of 

 Honolulu might be expected to throw light on the history of 

 Punchbowl. 



1. A well in "Thomas Square," just south of Punchbowl, 

 afforded the following section. 



Soil 6 feet, with 6 of black sand and "clay" 4 16 ft. ... 



White coral rock... 200 216 ft. 



Brown clay 44 260 



Coral rock 10 270 



Brown clay _ _ 60 330 



White coral rock 50 380 



Brown clay 80 460 



Bed rock or lava, penetrated . 49 509 



2. In " Mr. Ward's well," below Thomas Square, on King 

 street, there were at the top 15 feet of loam and sand, then 180 

 feet of "hard coral rock," carrying the depth to 195 feet; 

 again 24 feet of coral and shells above the 219-foot level ; and 



