GEOLOGY AND TOPOGRAPHY OF HAAVAII. 129 



In 1910 steam bricks were made at :\Ioiliili from pulverized lava by an elaborate 

 process, biit, owing to unexpected chemical changes, the bricks were found to 

 be inferior in quality, and the process and product altered after an expensive 

 experiment. Lime manufactured from coral rock has long been a common 

 commodity in the islands, but it has never been considered quite equal to that 

 manufactured from limestone on the mainland. Sandstone of a fair i|\iality 

 occurs at several points about the island. St. Andrew's Cathedral, in Honolulu, 

 is made of sandstone imported from England long before Hawaii became an 

 integral part of the United States. When a few years ago it was decided to 

 enlarge the cathedral, the import duty made it impracticable to go to the same 

 source for more stone. A large part of the United States was unsuccessfully 

 hunted over for a match to the English stone. It was finally fimnd near Ear- 

 lier "s Point, about tv/enty miles from the cathedral site. This local stone is pleas- 

 ing in color and durable in quality. The hard, compact, dark bluish-grey basalt 

 is nuich used in liuilding operations whenever cut stone is required. A num- 

 ber of the mcst substantial .structures in the islands are made entirely of cut 

 stone derived from quarries usually ojiened in the vicinity of the particuL-ir 

 structure in which the stone is used. 



iluch of the softer grade of l)asalt is used in concrete and in mad coiistrnc- 

 tion. Beach sand is also used in mortar and to some extent on the roads, and 

 as road dressing. It is usually mixed with coral rock, the whole being rolled 

 together and oiled to form a smooth surface. Sand from beds in the neighltor- 

 hood of the Waianae Mountains is also used extensively in building operations, 

 but being formed from coral and shells it is undoubtedly inferior in (pudity 

 when compared with the sharp sand brought from the mainland. Salt is still 

 manufactured on the island by evaporating the sea water in shallow ponds along 

 tlie sea shore, but the main supply is imported. The use of the loose rough field 

 stone cir "moss stone" has recently come much into vogue for foundation and 

 ti'im work and has added much to the rustic as well as permanent appearance 

 of the bungalow homes, in the liuilding of whicli it is being extensively use 1. 



This already lengthy chapter on the geology of Oahu would be inconqilete 

 without some brief reference to a few of the more interesting, though minor, 

 natural features of the island which are obiects of interest to residents and 

 tourists alike. Among these may lie mentioned the numerous natural caves 

 fiirmcd in the volcanic rock. One at the west end of Judd street, a portion of 

 w liicli was (ini'e used as a burial cave, extends hack for several hundred feet by 

 a wintling, narrow passage. Other l)uri^d eaves are found above the road at 

 Wailupe Valley, and beyond, while alonu- tlie se:i coast, beyond Koko lleid, are 

 caves in wliich several interesting stone carving have been found. 



Points op Geologic Interest About O.vhit. 



The coast-line from Koko Head to .Makapuu Point is a region of much 

 geologic interest, with spouting horns, olivine crystal beaches, and nnich coast 

 scenery. The dash of waves against the exposed headlands at Koko Head and 



