The Phlegræan Fields Author(s): R. T. Günther Source: The Geographical Journal, Vol. 10, No. 4 (Oct., 1897), pp. 412-435 Published by: geographicalj Stable URL: http://www.jstor.org/stable/1774652 Accessed: 10-04-2016 09:12 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://about.jstor.org/terms JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. The Royal Geographical Society (with the Institute of British Geographers), Wiley are collaborating with JSTOR to digitize, preserve and extend access to The Geographical Journal This content downloaded from 194.27.18.18 on Sun, 10 Apr 2016 09:12:41 UTC All use subject to http://about.jstor.org/terms 412 THE PHLEGRXEAN FIELDS. prosperity of the country would, he thinks, be almost unbounded. There are some useful hints on outfit, which, while agreeing generally with the practice dictated by experience in India and other hot countries, differ in some points in accordance with the special require- ments of the climate. It will be new to many to learn that "people suffer much more from cold in British Central Africa than they do from heat." The chapter on botany, above alluded to, is followed by an equally valuable one on zoology. The concluding chapters on the natives of the Protectorate and their languages show much original research, and describe fully both the physical characters and the mental and moral traits of the various tribes. In the last chapter an attempt is made to trace the main lines of the Bantu dispersal from the site where their languages were first developed, placed by the author near the meeting-point of the Niger, Shari, and Congo basins. THE PHLEGREAAN FIELDS.* By R. T. GUNTHER, M.A., Magdalen College, Oxford. I WAS elected to the Oxford University Geographical Studentship for 1895-6 on March 14, 1895, for the purpose of enabling me to carry out certain investigations on the physiographical features of the Phlegraman Fields, near Naples. The objects proposed for research were- 1. The computation of the total quantity of matter erupted by each volcano and by all collectively, as an indication of the volcanic activity of the region. Owing to the ruined condition of many of the older craters, I have been met with many preliminary difficulties. I have, therefore, devoted myself chiefly to the enumeration of the more or less recognizable craters and to their relationships. 2. The examination of the valleys on the slopes of certain of the older craters, with the ultimate intention of collecting material from which it might be possible, at some future time, to arrive at a conclusion respecting the relative ages of those crater-slopes, and of the volcanoes themselves. A special study of the region was made during the Easter Vacation, 1895, at the Royal Geographical Society's library. I left England in order to commence work on the second of these objects on June 28. While engaged in the examina- tion of the valley beds, I lived at a small Osteria between the monastery of Camaldoli and the village of Nazaret. I had intended to reside at the monastery itself, but the monks refused their hospitality for more than a single night to one who could not pretend that he had lost his way in the woods. My work was chiefly on the erosion curves of valleys, and in plotting out their watersheds on a map. I returned to England after the end of the first week in September, and went out to Naples during the ensuing Christmas vacation, from December 12 until January 21. I resided at Naples, and made use of the Cumana railway for reaching the more distant volcanoes. It is with great pleasure that I take this opportunity of recording my deep sense of gratitude to the British Consul at Naples, Mr. E. Neville-Rolfe, to the monks at Camaldoli, and to the officers of the Stazione Zoologica, for the personal kindness they have severally extended to me on various occasions. The Royal Geographical Society has still further helped me with the loan of a surveyor's level and of an Amsler's planimeter. * For General Map (No. 1), see p. 464. This content downloaded from 194.27.18.18 on Sun, 10 Apr 2016 09:12:41 UTC All use subject to http://about.jstor.org/terms THE PHLEGREAN FIELDS. 41a I.-THE VOLCANOES. The Phlegreean Fields constitute but a small part of an immense area of volcanic deposits which cover all the lower stretches of country between Rocca- monfina and the Sorrentine peninsula, and which extend far up the western valleys of the Apennines to a distance of some 30 miles from the coast. On the east and south these volcanic deposits are bounded by the Tertiary limestone of the Apennines and the Sorrentine chain of hills. To the west they continue for an unknown distance below the depths of the Tyrrhenian basin of the Mediterranean. The submarine volcanic deposits cannot be of less extent than those which are now subaerial, for even at Capri beds of considerable thickness have been measured. Indeed, it does not seem improbable that the submarine deposits of the bay of Naples join those of Ventotiene and the Ponza islands, and they probably extend much further. In the vicinity of Naples, neither the tunnels that sanitary or railway engineers have driven through the hills, nor the deepest well shafts that have been sunk, have penetrated to the bottom of these deposits, or have reached any stratum of rock that is not of a volcanic origin. The well at Ponticelli was carried down 180'6 metres, through varying strata of volcanic debris, without reaching any other rock. The conclusion to be drawn is, that for such a thickness of volcanic rock to have been accumulated, the volcanic fires must have been alight for a very long period of time, yielding the energy which has lifted so much matter up from below and scattered it broadcast over the surface. The original volcanoes which laid the foundations of this tract of country must have teen buried over and over again by the debris vomited by other vents, which have in their turn been obliterated by the vast piles of ashes and lava ejected by more recent volcanoes. Were this all, the interpretation of the more recent history of the region would be an easy matter. But the older volcanoes, in addition to suffering sepulture, have as often been partially destroyed, either by their successors or by denudation by sea or rain. By denudation, the substance of many volcanic heaps has been dis- tributed over adjoining areas, and has often contributed to the effacement by burial of adjoining volcanic structures. The denudation of material from one volcano and its redisposition on or around another, the formation of new volcanoes, the burial of old ones, have gone on uninterruptedly, and have produced the physiographical aspect of the country as we know it at the present day. Some geologists tell us that most of the vast deposits of tufa which are so prominent a feature in the region, owe their present wide distribution to the action of sea-water, and that salt waves carried them to the valleys in the Apennines. Other geologists would have us believe that such a view is as unnecessary as it is absurd, and that the tufa deposits fell as dust and ashes from the air, and were somewhat compacted by rain-water. Others, again, would invoke the former existence of volcanic vents situated far from the areas where they occur to-day. At the present day all the volcanic vents which can be indubitably recognized as such are within some 5a miles of the coast-line between Vesuvius and Cumee. SUBDIVISION OF VOLCANIC AREA. The area under consideration may therefore be very naturally divided into two regions-the region of the volcanoes, and the region of the volcanic plains. The first region, of volcanoes, may be defined as that in which the actual volcanic vents are situated. It is characterized by its uneven nature, its burnt soils, its crater-like hills and hollows, volcanic ridges, and trachytic rocks. No. IV.- OCTCBER, 1897.] 2 E This content downloaded from 194.27.18.18 on Sun, 10 Apr 2016 09:12:41 UTC All use subject to http://about.jstor.org/terms 414 THE PHLEGR.EAN FIELDS. The second region, of volcanic plains, is that which contains no volcanic vents, but its rocks and soil are composed of volcanic debris ejected or denuded away from the first region and spread over the second region by water or other agency. It is characterized by its level stretches of volcanic soil, usually of the most fertile kind. This division is one which has long been recognized by the inhabitants of the Neapolitan provinces, who speak of the second flat region of fertile plains as the Campagna Felice, and of the first as the Campi Flegrsei. The Campi Phlegraei, or " Burning Fields," then, owe their character to the fact that within their confines the topographical features are chiefly the result of the assemblage of a number of craters of volcanic disturbance grouped in close proximity to one another. This region of volcanic vents extends over about 50 square miles, the greater part of which lie within a rectangle measuring 12 miles from east to west, 5i from north to south.