PREFACE
During a sojourn in the Pacific, which covered a period of rather over a year in Hawaii (1896-97), and of two years and three months in Fiji (1897-99), my attention was mainly confined to the study of plant-distribution and to the examination of the geological structure of Vanua Levu.
With Hillebrand’s “Flora of Hawaii” always in my hands I roamed over the large island of Hawaii, ascending the three principal mountains of Mauna Kea, Mauna Loa, and Hualalai, and in the case of my second ascent of Mauna Loa spending twenty-three days alone on its summit. Similarly in Fiji, Seemann’s “Flora Vitiensis” was my counsellor and guide in the matter of plants.
In Hawaii I was in a land of active sub-aerial volcanoes, and I paid my devotions at all the altars of “Pele,” their presiding deity. In Fiji I trod upon the surface of submarine volcanoes that emerged ages since from the ocean and still retain their coverings of sea-deposits. Both in Hawaii and Fiji I lived much among the people; and though my chief interest lay in the comparison of these two types of volcanic islands, I could not but be drawn to the kindly natives whose hospitality I so long enjoyed.
Destiny led me to Vanua Levu in the following fashion. With the relief party to take me down from Mauna Loa there arrived a well-known German naturalist who, like myself, had been interested in coral-reef investigations. We discussed this warm topic at an elevation of nearly 14,000 feet above the sea, with the thermometer at 20° F. As we sipped our hot coffee and listened to the occasional “boom” from the bottom of the great crater, at the edge of which we were camped, I remarked to my friend that I was thinking of spending some months in Samoa. To this he good-humouredly replied that I might leave Samoa to his countrymen and describe one of the large islands of Fiji. International rivalry over that group of islands was then rather keen. However, Dr. K. went to Samoa, and I have now completed this volume on the geology of Vanua Levu, Fiji.
It will not be necessary to lay stress here on the difficulties and hardships connected with the exploration of little known tropical regions. Many will be familiar with all that these imply, where the rainfall ranges from 100 to 250 inches, where the forests are dense, where tracks are few and swollen rivers are numerous, and where the torrent’s bed presents often the only road.
The only extensive geological collections made in Fiji previous to my visit were those of Kleinschmidt in 1876-78, which together with a small collection previously made by Dr. Gräffe were examined by Dr. A. Wichmann. These rocks were obtained from Viti Levu, Kandavu, Ovalau, etc., but not from Vanua Levu. Dr. Wichmann’s paper of 1882, descriptive of these collections, presents us with the results of one of the earliest studies by modern methods of research of the volcanic rocks of the Pacific Islands. It is to this investigator that we are indebted for the establishment of the occurrence of plutonic rocks, such as granites, gabbros, diorites, in Viti Levu.
Although, as far as I can ascertain, few, if any, rocks have been specially described from Vanua Levu, this island was visited by Dana in 1840 when attached to the United States Exploring Expedition under Wilkes. His observations on its geology were published in his volume on the geology of the expedition. Although not extensive they are valuable from their reference to his discovery of trachytic and rhyolitic rocks as well as acid pumice-tuffs in the island. It is singular that his observations have apparently been overlooked by all his successors. Wichmann with this discovery unknown to him remarked on the seeming absence of quartz-bearing recent eruptive rocks from the South Seas.
When the “Challenger” Expedition visited the group in 1875 some geological collections were made which were described by Prof. Renard in the second volume on the “Physics and Chemistry” of the expedition. No collections, however, were made in Vanua Levu. In 1878 Mr. John Horne, Director of the Botanic Gardens at Mauritius, made some important observations on the geological structure of this island and of other parts of the group, which he published in his account of the islands given in “A Year in Fiji.” No collections were obtained by him; but prominence is given to his observations by Dr. Wichmann and others. Like Dana in the case of the acid volcanic rocks, Mr. Horne has forestalled me in his conclusion that Vanua Levu amongst the other larger islands has been formed mainly of the products of submarine eruptions.
The visit of Prof. A. Agassiz to Fiji in 1897-98 gave a fresh impetus to its geological investigation. We are indebted to him not only for his own extensive memoir on the islands and coral reefs of this group, but also for the subsequent important explorations of Mr. E. C. Andrews and Mr. B. Sawyer in Viti Levu and the Lau Islands. These two gentlemen have since published a short paper on the caves of these islands. Mr. Eakle has described the volcanic rocks collected during the visit of Prof. Agassiz. It is, however, noteworthy that, although the collections were made in Viti Levu, Kandavu and in many other of the smaller islands, Vanua Levu is not represented. Mr. Eakle’s conclusion that basic andesites and basalts are the characteristic rocks of the region, the augite-andesites predominating, would apply to Vanua Levu in great part. This island possesses also in fair amount hypersthene-andesites and dacitic or felsitic andesites, which are very scantily represented in the collections examined by Mr. Eakle. In connection with the quartz-porphyries and trachytic rocks which also occur in Vanua Levu, it should be observed that Mr. Andrews describes a rhyolite from Suva in Viti Levu. Unlike Viti Levu, Vanua Levu displays but a small development of plutonic rocks.