DERIVATION OF THE FLORA OF HAWAII 7 



tion of any activity within this crater, which is sheltered on the windward 

 side by walls 2,000 feet or more in height. The floor of the crater shows 

 lava flows that look as if they had been formed yesterday. 



From a study of the topography as well as of the fauna and flora of 

 the different islands, 2 it is generally agreed that Kauai, the northernmost 

 of the main group, is the oldest. The next large island, Oahu, upon which 

 is situated Honolulu, has two mountain ranges of different ages, one, the 

 Kaala range, being probably of about the same age as Kauai. The main 

 range of Oahu is more recent, and the Island of Molokai is of about the 

 same age. 



Maui, the second in size of the islands, is composed of two unequal 

 portions, a smaller and older part, West Maui, connected with the larger, 

 much more recent part by a low isthmus. The greater part of Maui is 

 composed of the great extinct volcano, Haleakala, over 10,000 feet in 

 height. The vast crater is over twenty miles in circumference and 2,000 

 to 3,000 feet in depth, and although the lava flows and cinder cones within 

 the crater look as if they had been formed very recently, there is no tradi- 

 tion among the natives of any eruptions. 



Much the largest of the islands is Hawaii, which comprises about 

 two-thirds of the total area of the archipelago. It is composed of three 

 volcanic masses of different ages. The oldest region is the Kohala range, 

 which is much worn down. Next is the great cone of Mauna Kea, 13,805 

 feet in height, the loftiest mountain in Polynesia. There is no record of 

 activity in this mountain. At the present day the volcanic activity is con- 

 fined to the two craters of Mauna Loa, but a lower cone, Hualalai, has 

 been active within a century. The summit of Mauna Loa is nearly as high 

 as Mauna Kea (13,675 feet) and is occupied by an active crater. On 

 the flank of the mountain is the great pit crater, Kilauea, now a familiar 

 sight to the tourist. Hillebrand 3 summarizes the formations of the islands 

 as follows, in point of age: 1, Mauna Loa; 2, Hualalai; 3, Haleakala; 

 4, Mauna Kea; 5, Kohala range (Hawaii) and West Maui; 6, Molokai 

 and main range of Oahu ; 7, Kaala range of Oahu, and Kauai. 



Considering the latitude, the temperatures are very moderate. In 

 Honolulu, at sea level, the highest temperature recorded from 1904-1909 

 was 86, the lowest 56. 



RAINFALL 



The precipitation shows extraordinary variation within short dis- 

 tances. While in Honolulu the annual rainfall is only about thirty inches, 

 in the valleys a few miles back of the town it may be more than four times 



2 Hillebrand, W. : "Flora of the Hawaiian Islands," Introduction, pp. xviii- 

 xxii. 1888. 



3 Loc. cit., p. xxi. 



