260 S. Powers — Notes on Hawaiian Petrology. 



nodules and masses of white or grey clay remain. Frag- 

 ments of some of the nodules on the application of water 

 swell to many times their original size. A bed of white 

 clay 10 feet in thickness is reported on the northwest side 

 of the island. 



Wailau volcano is judged to have consisted largely of 

 feldspar basalt with rare alkali trachyte. In composition 

 and appearance the lavas of Kohala, on Hawaii, most 

 nearly resembles this volcano. A greyish blue feldspar 

 basalt with feldspar crystals sometimes one or two 

 inches long and % inch thick compose a number of flows 

 along the south shore and in the gulches on the north. 

 Olivine basalt dikes occur in Halawa and in Wailau 

 gulches, and gabbro, as described below, is found in 

 "Wailau gulch. Kalaupapa, the peninsula north of the 

 fault-scarp, now used as a leper colony, is composed of 

 young olivine basalt which has poured out of three small 

 vents arranged in a line perpendicular to the main fault. 



Lanal. — Lanai appears to be composed of olivine and 

 feldspar basalt in about equal amounts. The original 

 center of eruption has been degraded, but several broad 

 depressions resembling small bolsons occur south of the 

 present summit. These depressions may represent 

 secondary craters or possibly wind-blown depressions. 

 A a flows of much younger age than the major portion of 

 the mountain occur on the southeast and north sides. 

 That on the north, near Maunalei valley, is the less 

 weathered. Nodules of clay like those so common on 

 West Molokai and a few nodules of chert are found in 

 the residual soil of the south side of the island. 



Kahoolaive. — Kahoolawe is a barren island west of 

 Haleakala inhabited by one Japanese caretaker. The 

 vegetation has been destroyed by sheep and goats so that 

 the surface of the island is barren, weathering basalt 

 forming a red residual soil. Clouds of the soil blow out 

 to sea with the strong trade winds. Seven cones and 

 four cone-craters are shown on the IT. S. Coast & Geodetic 

 Survey contour map of the island (-Gig. 2). 



Specimens were collected near Conradt's landing on 

 the north side of the island. The shore clirls are com- 

 posed of a fine-grained, minutely vesicular olivine basalt 

 of grey color which, under the microscope, shows 

 olivine phenocrysts in a groundmass of glass, small feld- 

 spar laths, augite and magnetite crystals, and masses of 

 limonite, the latter being in part in branching patterns. 



