THE DERIVATION OF THE FLORA OF HAWAII 



Owing to their extreme isolation, the Hawaiian Islands are of special 

 interest both to the geographer and the biologist. With a combined area 

 of 6,454 square miles, they are further removed from any continental area 

 than is any other region of equal size upon the globe. They are 2,000 

 miles from North America, the nearest continent, and the nearest islands 

 of any importance, the Marquesas, are 1,860 miles distant. 



There are two very different views held as to the origin of the 

 archipelago. The one most commonly accepted is that the islands, which 

 are entirely volcanic, were thrown up by volcanic activity from the ocean 

 depths, and that they have always been completely isolated. At present 

 the archipelago is surrounded by very deep water. Within forty miles of 

 the shores the ocean is upward of 10,000 feet in depth, and between the 

 islands and the American coast is an enormous area of deep water, in 

 places reaching more than 20,000 feet in depth. 



It is believed by some students of the subject, however, that the 

 islands have not always been so isolated as at present. This view has 

 recently been taken by Pilsbry. 1 The advocates of this theory believe 

 that there was formerly a much larger area of land in the Pacific, includ- 

 ing Hawaii, which was connected more or less intimately with the great 

 land masses of the Southern Pacific, now represented by Australasia and 

 Indo-Malaysia. The multitude of islands constituting Polynesia is be- 

 lieved to be merely the remains of a once extensive land mass, either a 

 single continent, or several large continental islands, like Australia. 

 This great continental area has been undergoing subsidence since early 

 Tertiary times, and the islands now existing are the tips of mountain 

 masses, often volcanic, superimposed upon this submerged continental 

 area. 



Should this latter hypothesis prove correct, we must assume that the 

 large volcanic masses, rising to nearly 14,000 feet in the case of Mauna 

 Kea, have been formed upon a land area which has sunk in the course of 

 ages as many feet below its former level, since on nearly all sides the 

 archipelago is at present surrounded by very deep water. 



To the northwest of the main group there extends a chain of small 

 islands evidently formed along the same line, and connected by relatively 



1 Pilsbry, H. A. : "Mid-Pacific Land- Snail Faunas," Proc. Nat. Acad. Sci., 2, 

 429-433. 1916. 



