veils he th st frtebe dele ranle Ge lets jale pojerege ent # fy ate tant hemor fo Gn bebe het of arndesoie yas sei eset’ = ebro ray rreeni penetcprerr oy = = npr e nn ts re eiatw in + Ea gainorenss pois saws * eegetebesdeue cath Sd rt Lex hint sc etd saeioepnas tees Sen te ee a ae oe in) oe UNITED STATES EXPLORING EXPEDITION, “VNVC ‘aT Ad azennk KYEI@ Sleeve | oe MHL JO perpen LOY Ms | OTE hax as / puery ne ue, memyebiyy | nya ys zowog XMS seg | sour, 20 OIStIU AL “S$ Ren Ne ap - 4 ie 2 30, EXPLORING EXPEDITION, ey . DURING THE YEARS 1838, 1839, 1840, 1841, 1842. Vi | Or gaa, UNDER THE COMMAND OF CHARLES WILKES, U.S.N. (5 EK O L Q (+ ae , : 7 BY ry (YH 166 © “q JAMES D. DANA, AM, at AIRE : v S bn 4 / INO ; e GEOLOGIST OF THE EXPEDITION, — b8Gnjan vere = MEMBER OF THE SOC. CHS. NAT. CUR. OF MOSCOW, THE SOC. PHILOMATHIQUE OF PARIS, fi THE AMERICAN ACADEMY OF ARTS AND SCIENCES AT BOSTON, ETC. _ : WITH A FOLIO ATLAS OF TWENTY-ONE PLATES. l(JU@~7ex 5 6 NEW YORK: GEO. P. PUTNAM, 155 BROADWAY. LONDON: PUTNAM’S AMERICAN AGENCY, 49 BOW LANE, CHEAPSIDE. ie. eg . an ; eae ee ee ae ee TABLE OF CONTENTS. _Cuap. I, General Remarks on the Pacific Ocean, - . : - Topography, - - : - : - = oan General Geological Constitution of Islands, - - - Geological agencies, —- : - é ¢ : Cuap. II. On Coral Formations, - : - : - - 1, Features and Structure, - : : 5 4 General Remarks, - : : : 2 Fringing and Barrier Reefs, - - : : Forms, - - : 5 4 a Structure, - - - A 7 : Thickness, : 5 : : : Coral Islands, - - . : : s Forms, - : : 3 : : Structure, - 2 2 & Completed Coral Island, - ° ° 3 2. On Coral Zoophytes, . - : é mc Structure and growth, - *> a 2 ‘ Texture and composition of Corals, - - s Causes influencing growth, - : - - Rate of growth, - - : os. P 3. Formation of Reefs and causes of their features and Geographi- cal Distribution, - E . 4 2 Formation, : S : : : 2 Causes modifying their forms and growth, - - * Rate of growth of Reefs, - : : < 2 Gugin of forms of Barrier Reefs and Atolls, —- eographical Distribution, - . - : : 4, Geological Conclusions, - - - c : Cuar. III. On the Hawaiian Islands, - : E z : : 1. Island of Hawaii, 101 103 103 114 121 123 134 147 155 158 al CONTENTS. General Features, - - 3 Volcanoes, - c : 2 Mount Loa, : 2 i Kilauea, - = C : Eruptions, - - : General Conclusions, - - Summit Crater of Mount Loa, - Subordinate Craters of Mount Loa, — - Mount Kea, - a : Mount Hualalai, - : s General Conclusions on Volcanic Action, 2. Island of Maui, - E 2 : 3. Kahoolawe, Lanai, and Molokai, - - 4, Island of Oahu, - : : A General Features, : C E Eastern Division, - - : & Mountains, : Z 4 Lateral Craters, - = = Western Division, - “ Coral Formations, - = : z General Conclusions, - - - 5. Island of Kauai, : : - 2 General Features, - i é Geological Structure, : - - Craters of Koloa, : S Coral Formations, - c - Z General Conclusions, - E 6. General remarks on the origin of the Hawaiian Cuap. LV. Society Islands, - - : : 1. Island of ‘Tahiti, e 2 : - 2. Other Islands of the Group, - 5 Cuap. V. Samoan Islands, - : 2 “ z 1. Manua, Ofu, Olosenga, and Rose Islands, 2. Island of Tutuila, — - - : : 3. Island of Upolu, - - : = General Features, - = 2 : Geological Structure, - - - Extinct Craters, - - : - Era of Eruptions and subsequent changes, 4. Manono, Apolima, Savali,_ - - - 5. Concluding Remarks, — - - - Cuap. VI. Viti or Feejee Islands, - - - - CONTENTS. vii PAGE Cnap. VII. Pacific Ocean, : - : - 2 = 353 1. General Review of Volcanic Action, - = : pe Bios} On Cinder Cones, : - - : = 354 On Tufa Cones, - - - - - - 3855 On Lava Cones, - : : - : 355 Influence of fluidity of Lavas, - E - = 358 Influence of Fissure Eruptions, — - - - 360 Solid Centre of Volcanic Mountains, - - - 9864 Rapidity of formation, - - - - 365 Conclusions, with remarks on von Buch’s theory of elevation- craters, - - - F - - 366 2. Origin of Lithological Characters of Islands, - - - 3872 3. Origin of Valleys, - - - - - 379 4, Changes of Level, - - - - - - 392 Subsidence indicated by Atolls and Barrier Reefs, - 394 Elevations of modern eras, - - - - 402 Changes of level preceding Coral Reefs, - - 412 5. General arrangement of lands in the Pacific, - - - 414 6. Origin of the general features of the Pacific and of the Globe, 424 Cuae. VIII. On New Zealand, - = = 2 = : 437 Cuap. IX. On New South Wales, = = - = : - 449 1. Geological formations, A z : 456 2. Sydney Sandstone formation, - - - - 459 3. Coal formation, - - = - = = 469 4. Sandstone strata below the Coal, : = = - 484 5. Basaltic and allied Rocks, - : - E 495 6. Circumstances attending the origin of the Deposits, — - - 516 7. Degradation and Denudation, - - - - 526 8. Evidences of Change of Level, - - - - 533 Cuap. X. On the Philippine and Sooloo Islands, — - - - - 539 Cuap, XI. On Deception Island, - - - : = = ysl Cuapv. XII. On Madeira, - = ? : : . 549 Cuap. XIII. On a part of Chili, 7 S : 5 - - 557 1. Granitic Rocks and Veins near Valparaiso, - - 561 2. Greenstone, Basaltic and Porphyritic Rocks, - - - 9579 3. Sedimentary Rocks, - : - : A 583 Cuapr. XIV. On the vicinity of Lima, Peru, - = : : - 587 1. Recent deposits of the coast near Callao and on San Lorenzo, 588 Vill Cuap. XV. On the vicinity of Nassau Bay, Tierra del Fuego, Cuap. XVJ. On the vicinity of Rio Negro, Crap. XVIT. On Oregon and Northern California, AppEenpix I,—1. Fossils of New South Wales, 2. Fossils of Tierra del Fuego and Peru, Aprenpix II. INDEX, CONTENTS. 2. Secondary Rocks of San Lorenzo, 3. Rotation by an Earthquake, - 1. General Features, - 2. Geological Structure, Granitic and Associated Rocks, Older Sedimentary Rocks, Basalt and other recent Igneous Rocks, Tertiary Formation, River Terraces and Beach Formations, - Causes of Features, and Changes in Elevation, Fiords, evidence of Change of Level, 3. Fossils of Oregon, Page 31 33. 41, 46. 50. 53. 58. 61. 91. 109. 115. 117. 118, 127, 130 [LEUSTRATIONS* An island surrounded by coral reefs, barrier and fringing. Clermont Tonnerre, one of the Paumotu Atolls, from a drawing by A, T, Agate. Map of part of the north shore of Tahiti, from Matavai to Papieti, with the reefs of the shore in dotted outline, (spaces included by the dotted lines.) Point Venus is the east cape of Matavai Harbour; Oxe Tree Hill occu- pies the west point. Map copied from the chart made by the Expedition. Bluffs of coral sand-rock, north shore of Oahu. Map of the Kingsmill or Tarawan Islands, from the charts of the Expedition, Maps of the Islands Taiara; Henuake, Honden or Dog Island; Swain’s Island; Jarvis Island; Fakaafo or Bowditch. From the charts of the Expedition. Section of a coral island reef from the ocean to the lagoon. Figures 1, 2, 3, blocks of coral rock standing on the reefs of coral islands, Figures of crystals of gypsum. View of an island in the Bay of Islands, New Zealand, called “‘’The Old Hat.” Harbour of Apia, north side of Upolu, Samoa. From the charts of the Expe- dition, Harbour of Falifa. Ibid. Whippey Harbour, Viti Lebu; a, the entrance through the reef. Ibid. Figure 1.—Section showing the effects of the subsidence of an island sur- rounded by coral reefs ; 1, 11, 111, 1v, different water levels; ff’, f'",f'", sections of fringing reefs; 0b’, b'', 6’, barrier reefs; c’, c’’, c’’’, channels within barrier reefs ; 2’"’ Figure 2. Aiva Island, one of the eastern Feejees, surrounded by a distant , islets of coral reef in channel. barrier. Figure 3. Sectional sketch of Aiva Island. Gambier Group, one of the Southern Paumotus. * From sketches by the author, except when otherwise stated. Cc x Page 131. 132, 159. 169. 178. 174. ids 185. 190. 206. 219. 220. 226, 228. 229, 232, 236. 240. 241, 242, 243. 244, 245. 246, 248. 249. 253, 254. 250. 271. ILLUSTRATIONS. Figure 5.—Section showing the effects of subsidence in producing and chang- ing an atoll, a continuation of fig. 1, p. 127; 1v, corresponds to rv fig. 1 ; v, vi, other water levels. Figure 6.—Same as figure 5, with the water level at v1; but the emerged reefs widened after a cessation of subsidence. Figure 7.—An island with a barrier reef, in which the reef is widened and surmounted by vegetation, after a cessation of subsidence. Outline view of Mount Loa and Mount Kea, showing angle of slope. Part of Eastern Hawaii. Kilauea, as seen from above; from a sketch in the Narrative of the Expedi- tion, iv. 165. Vertical cross section of Kilauea. Spire of lava seen in Kilauea ; height forty feet. View of part of Kilauea, by Lieut. Malden; taken in 1825. Sandhills of Nanawale. Summit crater of Mount Loa, as seen from above; from a sketch in the Nar- rative of the Expedition, iv. 111. Section of Mount Loa, showing its actual slopes, and an ideal view of the central conduit of the mountain, and that of Kilauea. Diagram, illustrating a probable convergence of the two conduits. Island of Maui, in outline. Crater of Hale-a-kala, from a drawing by Mr. J. Drayton. See Narrative of the Expedition, iv. 254, Part of southeast side of Maui, showing course of last great eruption of the crater. Outlines of Kahoolawe, Molokai and Lanai. Island of Kahoolawe. Part of the Koolau Precipice, as seen from the north, with the peak Kona- huanui, and the “ Pali” or precipice at the head of the valley of Nuuanu to the west of the peak. The Tufa Crater, Diamond Hill, on Southern Oahu. Diamond Hill and the small crater at the foot of the mountains, Koko Head craters ; a bird’s eye view, a little oblique. Koko Head craters, as seen looking west. Koko Head craters, seen from the east. Map of salt-lake region, Oahu. View of bluffs enclosing salt-lake region, as seen from Honolulu harbour. Map of Kaneohe Point, with its craters. Outline of crater of Kaneohe Point, as seen from the northwest, with a sepa- rate view of the large crater on the point. Isolated mass of coral rock rising from the reef of Waialua. Bluffs of drift sand-rock, northern Oahu, near Kahuku Point. Figures 1, 2, 3, sections of drift sand-rock, showing the character of the lami- nation. Map of craters of Koloa, Kauai. At the projecting point, on the left, is the site of the bluff of drift sand-rock, figured on page 277. J ry h , + Page 272. 277. 283. 2805. 297. 307. ILLUSTRATIONS. Xi View of craters of Koloa, taken from the bluff of drift sand-rock. There is much less vegetation in the scene than the view presents. Bluff of drift sand-rock. Map, illustrating origin of Hawaiian Group. Outline view of island of Eimeo, Society Group. Curved columnar structure in basalt, on Tahiti. Map of the Samoan or Navigator Islands, from the charts of the Expedition. . Crater of Tafua, Upolu, near Fasetootai. 319. Outline of western district of Upolu, as seen at sea, off Apia, north of the island. 325. Figure 1.—Outline of eastern district, as seen from the northwest. Figure 2.—Ibid., as seen from the southeast; A, crater of Olomanga ; B, Fan- ganga; C, D, E, summits of other craters, 327. Tufa crater, on island of Nuutele, as seen from the northwest and southeast. 334, Outline of Savaii, as seen from the southeast, with Apolima (@), and Manono (5), in front of Savaii. Figure 2, north extremity, more enlarged. 354, Outline of Assumption Island, one of the northern Ladrones, showing its actual slopes, 388. Diagram, illustrating the valleys of Tahiti. 442, Island ‘‘ Old Hat,” in the Bay of Islands, New Zealand. 443, “The Black Rocks,” Bay of Islands. 444, Extinct crater of Poerua. 459. East and west section through Illawarra, from the sea-port Wollongong. 462. Section, showing structure of Sydney sandstone, 463. Ibid. 464, Ibid. 465. Concentric structure in the Sydney sandstone, in the Illawarra range. 467. View of the North and South Heads of Port Jackson, N.S. W., the former in 503. 506. the distance ; taken from the South Head, looking north; shows rectangular fissures of sandstone layer at the water level. . View of the island Nobby, and Telegraph Hill at Newcastle, at the mouth of the Hunter; taken from the westward. . Diagrams, illustrating faults in the Newcastle coal beds. . Sandstone intersected by walls of ironstone. . Prismatic calcareous concretions from Glendon. . Sketch of a silicified stump, Illawarra. . Concentric structure and fissures in sandstone at Wollongong, Illawarra. . Ebid. . Basaltic columns, near Kiama, Illawarra. . Entrance of the Kiama Blow-hole. . Figures 1, 2, 3, 4, 5, 6, views of cliffs, showing the relative positions of basaltic layers and sandstone. . Figures 7, 8, 9, 10, connexion of basalt and basaltic conglomerate. Figure 9, same as dike No. 17, page 505. Map sketch of jaspery seams in basaltic conglomerate. Dike of basalt, near Wollongong. Xll Page 507. 508. 510. 511. 513. 515. 5381. 534, 553. 562, 563, 567, 568. 569. 570. O72, 573. 574. 589. 594, 599, 644. 649. 650. 655. 657. 660. 662, 663. ILLUSTRATIONS. Figures 2, 8, 4, 5, basaltic dikes in Illawarra, much faulted. Figure 2. Dike in second cliff south of Kiama, (same as No. 18, page 506.) Figure 3. Dike near Kiama Blow-hole, (No. 16, page 505.) Figure 4, dike in second cliff north of Kiama (No. 10 on page 505); slide two feet. Figure 5. Dike in same cliff, (No. 6 on page 505.) View of basaltic rocks, second point north of Kiama. Curved columns, as seen looking from above obliquely; from shores south of Kiama. Sketch showing structure of a basaltic dike. View of part of island of Nobby, intersected by a basaltic dike. Nodules of chalcedony in the basalt of Kiama, having an ear-drop shape. From a quarry of basalt, at Prospect Hill, near Paramatta. Diagram, illustrating the formation of valleys. Outline of beaches in Illawarra. Figures 1, 2, 3, basaltic cliffs, intersected by dikes, near Canigal, island of Madeira. Sketches of veins and beds of hornblendic rock in granite, near Valparaiso. Ibid. Epidotic seams in granite, near Valparaiso. Figures 6, 7, views of two compound granitic veins in gneissoid granite, with the direction of the micaceous structure of the adjoining or included rock indicated. Figure 8, another view of same veins. Figure 9, a striped vein in granite. Figures 10, 11, 12, 13, faulted veins of granite. Figures 14, 15, 16, faulted veins of granite. Figure 17, faulted vein of granite. Figures 1, 2, crystals of gypsum, from the Callao cliffs, Peru. Figures 1, 2, sections of San Lorenzo beds. Entrance of ‘ El Paseo de los Agoas,’”’ Lima, showing the upper stones of the obelisk as revolved by an earthquake; sketch by J. Drayton. Mount Swalalahos or Saddle Hill, Oregon. Figures 1, 2, views of the Sacramento Bute. Bluff of laminated trachyte, Sacramento Bute. Dikes of sandstone intersecting tertiary rocks, Oregon. Figures 1, 2, calcareous crystallizations from concretions, Oregon. Figure 1, section of the alluvial plain of the Willammet. Figure 2, section showing terraces on the Umpqua. Figures 3, 4, sections illustrating terraces on the Shasty. Figures 5, 6, 7, 8, sections illustrating terraces on the Sacramento. GeO LILO) Ge x, CHAPTER 1. GENERAL REMARKS ON THE ISLANDS OFTHE PACIFIC OCEAN. Tue Pacific Ocean, between the coast of America on the one side, and Asia, the East Indies and New Holland on the other, Behring’s Straits on the north, and the parallel of 66° south, covers more than sixty-two millions of square miles, and exceeds by ten millions of square miles the area of all the continents and islands of the globe.* About six hundred and seventy-five islands are scattered over this expanse of waters: but though so great their number, the surface of the whole, exclusive of New Zealand, does not exceed eighty thousand square miles, an extent little beyond New Zealand alone. Excepting also from the estimate New Caledonia, the Salomon Group, and other large islands in the southeast part of the ocean, lying between them and New Guinea, there are but forty thousand square miles, (less than the State of New York,) for the six hundred islands remaining. * The fact above stated is deduced from the calculation of 8S. P. Rigaud on the “ Relative Quantities of Land and Water on the Terraqueous Globe,” in the Transactions of the Cambridge Philosophical Society, (England,) vol. vi., 1837, p. 289. From his results we learn that out of a thousand parts, into which he divides the world, there are contained in the Pacific Ocean, in The North temperate zone, - - - - 72°3793 parts. The North torrid zone, - - - - 70°8383 “ The South torrid zone, - - - - 77:0000 nearly. The South temperate zone - - - - 95-9685 parts. The whole Pacific Ocean contains - - - - 3161861 “ The land of the world amounts to” - - - - 265°9233 «“ 10 GEOLOGY. Yet this small area of land presents us with mountains 14,000 feet in height; volcanoes of unrivalled magnitude ; peaks, crags and gorges of Alpine boldness. And amid the wildness and grandeur of these scenes, many of which would well aid our conceptions of a world in ruins, the palm, the tree-fern, and other tropical productions flourish with singular luxuriance. Zoophytes, moreover, spread the sea-bottom near the shores with flowers, and form islands with groves of verdure above, and coral gardens beneath the water. ‘There is no part of the world where rocks, waterfalls and foliage are displayed in greater variety, or where the sublime and picturesque mingle in stranger combinations. These statements may seem incredible to those who have traversed only the surface of our own land; yet it will be in some degree com- prehended when the agencies that have operated to produce the results are considered :—that through every part there has been the vol- cano to build up mountains, and to shatter again its structures; a vast ocean to surge against exposed shores; rapid declivities to give force to descending torrents; besides a climate to favour the coral shrubbery of the ocean, and bury in foliage the most craggy steeps. Under such circumstances, 1t is not surprising that these ocean lands should be replete with attractions alike to the eye of taste and of science. The waters abound in fish, mollusks, echini, crabs and other forms of crustacea, asterias or starfish, and the variously coloured actinias or sea-flowers; and the fresh waters, although the islands stand isolated in the ocean, have their own species of fish, reptiles, and even Unionide. Yet with all the profuseness of life, animal and vegetable, it is a little remarkable that, besides bats, a native land quadruped is not known in the whole ocean, though rats and mice from shipping are common everywhere. New Zealand, although as large as New England, cannot boast of a single native species, excepting perhaps a mouse of doubtful origin, and bats which have wings to aid them in migration. It is obvious that the geology of the Pacific Islands embraces topics of the widest importance. There are extensive rock formations in progress, proceeding from the waters through the agency of animal life;—there are other formations, exemplifying on a vast scale the operation of igneous causes in modifying the earth’s surface ;—there are also examples of denudation and disruption, commensurate with the magnitude of the mountain elevations. ‘These three great sources of change and progress in the earth’s history are abundantly illustrated. ISLANDS OF THE PACIFIC OCEAN. ill In our report on these topics, we may adopt the following order of arrangement :— Chap. I.—A general review of the topography of the Pacific Ocean, and the constitution of its islands. Chap. I1.—An account of coral reefs and islands, and of their mode of formation. Chap. Il].—General remarks on the basaltic or igneous islands of the Pacific. Chap. IV—VII.—Geological descriptions of the groups of Pacific Islands, in the following order :—Hawaiian, Tahitian or Society, Samoan or Navigator’s, and the Feejee Group. Chap. VIII.—General considerations respecting the Pacific. General review of volcanic action in the Pacific. Mineral constitution of the basaltic islands. Origin of the valleys of the islands. Changes of level in the Pacific. General arrangement of land in the Pacific. Origin of the general features of the Pacific, and bearing of the facts upon the cause of the prominent features of the globe. Gt ee Ii TOPOGRAPHY OF THE OCEAN AND CONSTITUTION OP TES TiSi.AAN Dis: 1. Geographical Distribution of the Islands.* Reviewing the ocean simply with reference to the relative position of land and water, we observe the striking fact that the islands are * It is important to the reader to be acquainted with the ethnographic distribution of islands in the Pacific; and we here give a brief notice of it, gathered from the Report on Ethnography, by our philologist, Mr. Horatio Hale. The Pacific is divided into three large regions :—1, Polynesia; 2, Melanesia; and 3, Micronesia. The first diyision, Polynesia, includes all the islands of the middle and eastern parts of the ocean, comprising the Sandwich Islands on the north, New Zealand on the south, and the various clusters intermediate, with all the islands eastward of the same to the farthest limits of the Paumotu Archipelago. ‘The groups included (see the chart) are as follows :—orth of the equator, the Hawaiian; south of the equator, the Nukuhivan or Marquesas, the Paumotu, Tahitian or Society, Atiu or Hervey, Samoan or Navigator, 12 PACIFIC ISLANDS. confined, with few exceptions, to the latitudes within the tropical circles, 23 degrees 28 minutes either side of the equator. New Zea- land and a few associates on the south, and some small points north- west of the Hawaiian groups, are almost alone in exceeding these limits. A second fact, not less worthy of note, is found in the absence of islands, excepting an occasional one of small size, eight or ten in all, from the vicinity of the equator, between the Galapagos and the Carolines. This range of bare waters is more than 6000 miles long, or one-fourth the whole circumference of the globe; and it extends from five degrees south of the equator, to Hawaii, in latitude 19 degrees north. The large area between the South American coast and the Pau- motus, a distance of three thousand miles, is another wide blank in the Pacific, and we may view it as continuing westward with the same width, between the south tropical and antarctic circles. The newly discovered lands of the antarctic, extensively explored by the Iixpedition, under the direction of its energetic commander, form the southern boundary of this open sea. These facts are left for the present with this mere mention. They have a bearing on the geological history and dynamics of the ocean, which will be considered in a future chapter. Arrangement of the groups of islands.—The epithet scattered, as applied to the islands of the ocean, conveys a very incorrect idea of their positions. ‘There is a system in their arrangement, as regular as in the mountain heights of a continent; and ranges of elevations are indicated, as grand and extensive as any continent presents. Even a cursory glance at a map is sufficient to discover a general linear course in the groups, (as was long since remarked by Malte Brun and other geographers,) and a parallelism even between those in distant parts of the ocean. Thus the Hawaiian Islands stretch Fakaafo or Union, Phaenix, Vaitupu or Ellice’s, Tongan or Friendly, and New Zealand. The Feejee Group is intermediate, philologically, between Melanesia and Polynesia. The second division, Melanesia, embraces the islands within twelve degrees of the north- east coast of New Holland. Starting from New Guinea, to which they are related, the groups are as follows :—Admiralty, New Britain, New Ireland, Salomon, Vanikoro, New Hebrides, New Caledonia, and Flinden’s Archipelago, together with many small islands distributed over the included area. The third division, Micronesia, comprises the Carolines, extending west and north to embrace the Pelews, the Ladrones, and some scattered islands beyond, and east and south to include the Radack, Ralick, and Tarawan or Kingsmill groups. TOPOGRAPHY. 13 along in a direct line to the northwest. The Marquesas also are mostly in a single range. The Tahitian Group, the Samoan, the Tongan, New Hebrides, New Caledonia, Salomon Islands, Radack and Ralick Islands, the Kingsmills, and the Ladrones are all distinctly linear groups. As this subject is one of both geographical and geological interest, and has been but imperfectly discussed in previous works, we pass in review the principal facts respecting the several groups of islands: and it will appear that its importance is not limited even by the Pacific Ocean, although nearly one-third of the whole surface of the globe; for it has an evident connexion with a system that pervades the world. The facts and any irregularities will be more correctly appreciated if the reader will first consider, with regard to ranges of mountains, that their courses often vary many degrees, even when a general linear direction is distinct. An exactly straight line is nowhere to be found, not even in a single ridge of a chain. This is apparent in any good map of the world. The peaks advance and retreat all along the line, and occasionally the mountains sweep around into some new direction, and then return again, more or less nearly, to their former course. Again we observe that there are often parallel ranges in the same chain, as is strikingly seen in the Alps, the Andes, and our own Alleghanies. The characters of fissures, or dikes, afford other hints that should be considered ; for they illustrate the operation of those internal forces, by which mountains have been uplifted; and even exemplify, as is generally admitted, the actual origin of many ranges of mountains. Facts illustrating this subject will be found in our descriptions of the Pacific Islands, and the Report on Hastern Australia. They show that fissures are generally a series of linear rents in some main direc- tion, and while they are often parallel, or in continued series, they are also sometimes arranged in a series of overlapping lines, and may be curved or straight in the separate rents, as well as curved or straight in the long composite ranges of rents.* They are often accompanied by transverse rents, at night angles with the general system. The several groups of islands may be considered in succession. a. Hawanan Islands.—The Hawaiian Islands -proper, extend from Hawaii to Nihau, (see preceding map,) a distance of four hundred * See American Journal of Science, ili. 2d Ser. p. 390. 4 14 PACIFIC ISLANDS. statute miles, and have the general trend N. 64° W. But the range of islands does not stop at the last mentioned: it is continued on to 175° east longitude. ‘This western portion appears to consist of two or three parts, each in advance, or a little south, of the preceding, like the interrupted series of many fissures. ‘The directions of the parts scarcely vary from that above given. Viewing the range as a whole, the line is slightly convex northeastward. We observe, moreover, that between the Island of Hawaii and Oahu, two parallel lines are indicated by the islands intermediate : one including the summits Maui and Molokai, with Mouna Kea on Hawaii; the other the islands Lanai and Kahoolawe, together with Mouna Hualalai and Mouna Loa on Hawaii, and the crater Kilauea. A transverse trend is apparent in the relative situation of Nihau and Kauai, ranging nearly at right angles with the course of the group. b. Nukuhivan Group.—The Nukuhivan or Marquesas Group lies in a parallel line with the Hawaiian. As nearly as can be estimated, the trend is N. 60° W. Following the line of this range on beyond the equator, we observe four small islands (the Fanning Group), lying in a single series nearly straight, and having the same trend. Although we may not assume any connexion between the Fanning and Nukuhivan Groups, the coincidence of range, as well as trend, is worthy of remark. c. Paumotu Archipelago.—Among the many islands which consti- tute this archipelago, there is no difficulty in distinguishing a general course from the northward and westward to the southward and east- ward, approaching N. 60° W. Even in the separate islands, the pre- vailing trend is approximately the same as may be seen in the enlarged chart in the Hydrographical Atlas.* From Kruesenstern’s and Dean’s Islands on the northwest, the atolls stretch along over the sea towards the Gambier or Mangareva Group; and this spot of high land, and Pitcairn’s beyond, with some other low islets, lie near its eastern extremity. d. Tahitian Group.—The Tahitian or Society Group, and also the Island of Tahiti itself, conform nearly to the direction of the Paumotus, the trend being about N. 62° W. In the line of the group, to the eastward and southward, there are several islets, lying in a series, * See also the Narrative of the Exploring Expedition, by C. Wilkes, vol. i. TOPOGRAPHY. 15 and others still beyond, which extend the line to longitude 136° W. There is little doubt that the whole should be included in one system or range. e. Atiu or Hervey Group.—South and west of Tahiti lie a number of small islands, the western of which have been called the Hervey Group. Like the preceding groups, they range from the northwest- ward to the southeastward. ‘They constitute two parallel lines; the northern contains Aitutaki, Atiu, and other Hervey Islands, and ex- tends eastward to Rurutu and Raivavai, with the trend N. 66° W.; the southern embraces Rarotonga, Roxburgh, and Mangaia, and may possibly be continued in Osborn’s Reef and Rapa, with the trend N. 65° W. f. Samoa or Navigator Group.—The same linear arrangement is apparent among the Samoas as elsewhere in the ocean. The trend is a little more westerly, or N. 68° W. The easternmost islands give a still more nearly east and west course to that extremity of the line. But examined on an enlarged chart,* it is obvious that Ofu, Manua, and Rose island constitute properly a parallel line, of like trend with the three western, and in analogy with the interrupted parallel lines of fissures already explained. g. Fakaafo or Union Group.—North of Samoa two hundred and sixty miles, are three small islands, which le so exactly in a direct line, that they merit separate mention. The trend is N. 58° W. h. Vadtupu or Elhce’s Group.—To the west of Fakaafo lie seven or eight small islands, constituting a line of which the general trend is N. 56° W. i. Tarawan or Kingsmill Group.—The Tarawan Islands lie under the equator, just to the north of the last-mentioned group. From Taputeouea, the southernmost, to Maiana (see chart beyond), the trend of the range, as well as of the separate islands, is N. 42° W.; and this line will embrace the two islands Onoutu and Hurd, one hundred to one hundred and fifty miles further to the southeast. The islands Hopper, Knox, Charlotte, lie in a line nearly parallel, a little to the eastward ; and Peru and Byron’s Islands, one hundred and fifty miles to the southeast, have the same direction and a corresponding position. The Tarawan Group, taken as a whole, trends N. 25° W. j. Marshall Islands, or Radack and Ralck Groups.—The linear ar- rangement in the Radack and Ralick Groups is as distinct as in any * See the chapter on the Samoan Islands. 16 PACIFIC ISLANDS. part of the ocean. The trend of the former, the easternmost, is N. 30° W.; and that of the latter N. 37° W. k. New Hebrides—The New Hebrides constitute a long range, trending N. 40° W. ]. New Caledonia.—New Caledonia, with its reefs, extends in a similar line, running N. 40° W. There is a distinct. line of islands, parallel with New Caledonia, a little to the westward: the Isle of Pines appears to constitute its southeastern termination. On the west of New Caledonia there is another line, the Flinders range, having the same course, or N. 45° W. m. Salomon Islands, to New Guinea.—A linear order and form is nowhere in the ocean more remarkable than in this southwestern part. The Salomon Islands trend N. 57° W. The continuation of the line in New Ireland becomes more westerly, or N. 65° W. The Louisiade Group and the north shores of New Guinea correspond to another range running in the same direction, and also approximating westward, more to an east and west direction. Just east of the Salomon Islands hes the range of Vanikoro, which trends nearly with the New Hebrides, or N. 44° W. Thus far in the ocean we have observed only a northwestward and southeastward trend, excepting some subordinate lines. A trans- verse direction characterizes the following groups. n. Tonga or Friendly Group.—The line of islands from Tonga- tabu to Vavau trends N. 20° E. to N. 24° E. o. Kermadec Isles —The Kermadec Isles form a line between Tonga and New Zealand, trending N. 15° E. p. New Zealand.—The northern extremity of New Zealand—the foot of the boot—corresponds in direction with the generality of the Pacific Islands, trending N. 50° W. But the body of the group ranges 1n a transverse direction, with a course of N. 30° E. Lord Auckland’s and Macquarie Island, to the southward, are in the same line. Chatham Island lies in a line with the north part of the island. q. Ladrones.—The southern half of this long series of islands trends N. 22° E.; but to the northward the direction approaches more nearly to north and south. ‘The line, taken as a whole, is slightly curved, with the convexity eastward, and extends in the general direction Ne OS Ei. r. Pelev Group.—The Pelews seem to connect the Ladrones with the Moluccas; but there is evidence in the positions of the islands that at least two parallel ranges are here included; the Matelotes, TOPOGRAPHY. 17 Yap, and Hunter forming one line, having the same trend with the southern extremity of the Ladrones, or about N. 22° E.; and the Pelews, with perhaps the islands to the southward, to Aiou, another line ranging N. 25° E. s. Feejee Islands—The Feejee Islands constitute a large cluster of scattered islands; but amid the apparent irregularity we observe a fact, which we shall hereafter show to be of much interest, that the easternmost islands range parallel with the Tonga Group, or N. 23° E., while on the west the two large islands constitute a line running N. 40° E. The linear arrangement thus traced out over the ocean, and marked out by lines on the preceding map of the Pacific, is more distinctly apparent the larger the chart or globe on which it is observed; and any appearance of hypothesis which the reader might suspect from the study of a small map will wholly disappear on the exami- nation of one of sufficient size to exhibit the exact positions and forms of the islands. ‘The enlarged charts of the several groups illustrating this volume, evince clearly this fact. We shall further consider in another place certain particulars to be derived from a more minute study of the positions of islands in particular groups. The facts de- tailed show certainly a most remarkable uniformity of direction. Running parallel, or nearly so, with the Sandwich Islands, we observe the Fanning Group, the Marquesan, Paumotu, Tahitian, Atiu, Sa- moan, Salomon, New Hebrides, New Caledonia, Vanikoro, Vaitupu, Kingsmills, Radack and Ralick Groups. Nearly every island of the ocean, over an area whose breadth is five thousand miles from north to south, may be shown to conform to this system, excepting a few groups pointed out as characterized by a transverse trend. ‘The facts brought forward are here presented in a tabular form for the con- venience of comparison and future reference. 1. Northwestward trend. Hawaiian Group - - - trends - : - N. 64° W. Nukuhivan - - : - ge - - N. 60° W. Fanning’s - - - - a - - - N. 60° W. Paumotu - - - - - ce - : : N. 60° W. Tahitian - - : - - ee - - - N. 62° W. Atiu—Atiu line - : : = “e : - - N. 66° W. Rarotonga line - - a - - - N. 65° W. Samoa - - - - - ge - - - N. 68° W. Fakaafo - - - - - ae - - - N. 58° W. 18 PACIFIC ISLANDS. Vaitupu - - : : - trends - - - N. 56° W. Tarawan - - - - - oe - N. 42° W. to N. 25° W. Marshall—Ralick line - - : o - - - N. 87° W. Radack line - - se - : - N. 30° W. Vanikoro - - - - : ac - - - N. 44° W. New Hebrides - - : - oc - - - N. 40° W. Britannia - - : : . ee - - - N. 40° W. New Caledonia - - : - sc - - - N. 40° W. Flinders” - - : - - 06 - - - N. 45° W. North extremity of New Zealand - ‘6 - - - N. 50° W. Salomon Islands - - - “ - - - N., 57° W. Louisiade to New Guinea - - ne - - - N. 56° W. New Ireland - - - - ec - - - N. 65° W. 2. Northeastward trend. Tonga Group” - - - - a6 - : - Ni22°58K. Feejees, Eastern side - -