APPENDIX. 

I. ARTESIAN WELLS ON SOUTHERN OAHU. 
On page 287 reference is made to artesian borings on Oahu of the Ha- 
waiian Islands, that descended through coral reef strata of much thickness 
and at large depths, which are believed to be good evidence of a former 
higher level of the island by some hundreds of feet, and therefore of a grad- 
ual subsidence since, the only doubt coming from the possibility that the coral 
rock at the lower levels may be not true reef rock but of pelagic origin. The 
following are the details as to fifteen of these borings in the area between 
the centre of the city of Honolulu and Diamond Head on the coast to 
the eastward. The level of the surface from which they start is not above 
thirty feet. 
The positions of these wells may be learned from the following map, — a 
reduced copy of a chart received from the surveyor general of the Hawaiian 
Islands, Prof. W. D. Alexander. Part of the shore region of Southern 
Oahu is here represented, from the city of Honolulu, on the west, to the 
tufa cone, Leahi or Diamond Head, whose southern brow has a height of 761 
feet. Puowaina, or Punchbowl, standing just back of Honolulu and 498 feet 
high, is also a tufa-crater. Rocky Hill, near Oahu College, and some low 
hills near by, appear to have been made by flows of lava from fissures of 
comparatively recent date. The large and deep valleys of the mountains 
Nuuanu and Manoa, and the narrower Palolo valley, open out on this shore- 
region near the northern limit of the map. 
The map also shows the position and width of the coral reef of the coast, 
and of the harbor of Honolulu, which owes its existence to the reef. The 
larger part of this shore-region is covered by the elevated fringing reef, which 
has a height above the sea of fifteen to twenty-five feet. Its surface is cov- 
ered by six to ten feet of a glassy black volcanic sand, which may have been 
ejected from the Rocky Hill vent, and four to six feet of surface soil. The 
borings descend through the soil and sand, and then the elevated fringing reef 
of coral limestone, to a bottom of solid lava, and intersect at some levels, 
besides coral rock, layers of tufa, lava, “clay,” sand or bowlders, which are 
