JO C. H. HITCH COCK — GEOLOGY. OF OAHU 



The city is surrounded by an interesting group of extinct secondary 

 volcanoes, resting on ancient basaltic Hows and adjacent to a coral reef 

 which girdles the whole island. 



First discovered in the fourteenth century, the islands were rarely seen 

 by civilized people before 1820, since which time visits of investigation 

 have gradually become quite numerous. A multitude of allusions to 

 volcanic or coralline formations are made in the writings of travelers, 

 historians, and missionaries, such references being primarily to the exist- 

 ing active volcanoes on the island of Hawaii and sparingly to the phe- 

 nomena on Oahu, all of which will be passed by in this sketch and 

 mention made only of several important publications. 



My observations were made in 1883, 1886, and during a year's residence, 

 commencing September 1, 1898. The present sketch is complete to the 

 extent of the author's information, but the work done has not been 

 equally distributed over the island. The part most fully investigated 

 was the neighborhood of Honolulu and the line of the Oahu Railway 

 and Land Company. 



Literature 



The earliest publication cited is that of the United States Exploring 

 Expedition under Captain Charles Wilkes, in 1841, and of which J. D. 

 Dana was the geologist. His report appeared in 1849. The same author 

 visited the island again in 1887, and adds to his early observations in 

 papers published shortly afterward in the American Journal of Science 

 and in " Characteristics of Volcanoes," 1890. In 1856 W. L. Green 

 published in the Sandwich Island Monthly, for June, a paper entitled 

 " Extinct Craters of Oahu.' 1 References to this island will be found also 

 in part II of his book, " The Vestiges of the Molten Globe," 1887. In 

 the Memoirs of the Boston Society of Natural History, 1868, William T. 

 Brigham has devoted several pages to the geology of this island. Captain 

 C. E. Dutton studied the geology of Oahu in 1882, and his account is 

 published in the Fourth Annual Report of the United States Geological 

 Survey, 1882-1883. Important suggestions have been presented by 

 Professor W. D. Alexander, surveyor general of the Hawaiian islands, and 

 by Professor A. B. Lyons, of Oahu College. Doctor Walter Maxwell has 

 printed, under the auspices of the Sugar Planters' Association, 1898, a 

 treatise on the " Lavas and Soils of the Hawaiian Islands," deriving many, 

 facts from Oahu. 



The topography of our map is based on the excellent map of the island 

 published by Professor W. D. Alexander in 1881, on the scale of 66 $ 00 . 



Samples of the rocks, minerals, and fossils about to be mentioned, and 



