ACTIVE VOLCANOES OF THE SOUTH SEAS 603 



TWO ACTIVE VOLCANOES OF THE SOUTH SEAS 



By Professor HENRY B. CRAMPTON 



BARNARD COLLEGE, COLUMBIA UNIVERSITY, AND THE AMERICAN MUSEUM OF 



NATURAL HISTORY 



IN the course of a fourth journey among the islands of the Pacific 

 Ocean, during the year 1909, the rare opportunity was presented 

 of making an ascent of the remarkably active volcano formed about 

 five years ago on the island of Savaii, the largest member of the Samoan 

 group. In addition, during a short stay in the Hawaiian Islands, a 

 visit was made to Kilauea, a volcano which in contrast with the former, 

 has a long geological history, for records of its intermittent periods of 

 activity cover more than a century. It is the purpose of the present 

 article to give a short general description of these two volcanoes. 



Under any circumstances such works of nature would arouse the 

 interest of a student of natural phenomena; but in my own case the 

 opportunity to study them was valuable for additional reasons. My 

 investigations of the distribution and evolution of the land snails of 

 Polynesia demanded a thorough exploration of volcanic islands of 

 greater age, islands that for many centuries have been sculptured by 

 the elements so as to display alternating ridges and valleys radiating 

 from their high central peaks. Tahiti is perhaps the most beautiful 

 example of such an island. One finds that the several islands of the 

 Pacific groups are of various geological ages, and consequently ex- 

 hibit different degrees of weathering. They thus constitute a series 

 showing how ancient rugged islands like Tahiti and Moorea have been 

 derived from newly formed volcanic mountains like those of the 

 Hawaiian and other groups, which possess relatively even sides of lava 

 fields unfurrowed by erosion. Furthermore the various islands scat- 

 tered throughout the vast areas of the Pacific Ocean are interesting to 

 the naturalist because of the evidences they give of great changes in the 

 level of the ocean bed, and also on account of the role played by corals 

 in the construction of many types of islands. With few exceptions the 

 islands occur in groups or chains suggesting the conclusion that they 

 are the peaks of a range of mountains formerly connected by lowlands 

 but now separated as the result of a subsidence of the ocean's floor. 

 Every one is familiar with the theory that a coral atoll, consisting of a 

 living reef bearing a more or less extensive series of coral islets, is 

 built upon such a volcanic peak, which, according to Darwin and 

 Dana, has been withdrawn below the water's level and overgrown by 

 coral as it slowly subsided. It may be, as Agassiz contends, that a coral 



