Islands of the World
Continental and Oceanic Islands
The multitude of small and apparently fragmentary bodies of land, called islands, form only about one-seventeenth part of the entire land surface of the globe.
Continental islands are situated in the immediate vicinity of the continents, and form properly a part of the continental structure. They have the same kinds of rocks and mountain forms, and the same varieties of plants and large animals, which are found on the neighboring coasts of the mainland.
The size of this class of islands varies extremely. Some are mere isolated rocks, while others occupy large areas, like the British Isles, Japan Islands and Madagascar; or, more extensive still, Papua and Borneo, each of which has an area exceeding two hundred thousand square miles.
The distinctive character of Oceanic islands is that they lie at a distance from the continents, in the midst of the ocean basins. They are always small, and, though sometimes forming lines, or bands, they more frequently occur in groups.
The rocks which make up the body of the continents and continental islands—sandstone, slate, granite, and the various metamorphic rocks—are entirely wanting in oceanic islands. The latter are composed either of volcanic substances, or of limestone. Hence they present much less variety in relief forms than the continental islands.
Forms of Volcanic Islands
The islands of volcanic origin are more or less circular in outline; are usually considerably elevated, with rapid slopes; and are of moderate size. Sometimes two or more volcanoes, clustered together, form a single island of larger size and more irregular outline.
Occasional islands rise but little above the surface of the sea, their craters being filled by sea water. Many, however, rise to Alpine heights—like the peaks of Hawaii, in the Hawaiian Islands, nearly fourteen thousand feet in elevation; Pico de Teyde, in the Canaries, fourteen thousand feet; and Tahiti, in the Society Islands, over seven thousand feet above the level of the sea.
Wonderful Structure of Coral Islands
Coral islands are among the most striking phenomena of the tropical seas. Whitsunday Island in the midst of the Pacific is an excellent example. Rising but a few feet above the surface of the ocean, it forms a narrow, unbroken, nearly circular ring, surrounding a central lagoon of quiet water. When first seen, it presents the aspects of an angry surf breaking on a white beach of coral sand, in strong contrast with the deep blue color of the sea. Behind this a garland of luxuriant vegetation, whose tropical beauty, enhanced by the noble cocoa-palm encircles the quiet waters of the lagoon, while all around spreads the broad blue sea.
TWO OF THE GREATEST MARVELS OF LAND AND SEA
THE GRAND CANYON OF THE COLORADO RIVER, ARIZONA
This greatest of nature’s gorges is more than twelve miles across, a mile deep, and extends over two hundred miles in length. This whole vast space has been sculptured by the wear of the river through countless centuries. Its unparalleled magnitude, its architectural forms and suggestions, and its wealth of color effects create a picture that is grand beyond description.
THE BARRIER CORAL REEF OF AUSTRALIA
This vast reef of coral islands was built by a colony of coral insects, or polyps, as innumerable as the stars of the Milky Way. It rose from the floor of the ocean, builded out of myriads upon myriads of the dead skeletons of these marvellous insects.
Combination of Volcanic and Coral Islands
A large number of volcanic islands in the Pacific are encircled by coral reefs, which, when near the shore, are called fringing reefs. When at a considerable distance, leaving a lagoon of quiet water between them and the volcanic island, they are termed barrier reefs.
Coral Reefs and Their Builders
Coral reefs are masses of limestone originally secreted, in the form of coral, by minute polyps which live in countless numbers in the tropical seas. The coral produced by a single community of polyps grows chiefly upward; but multitudes of distinct communities often live so near together that the small lateral growth of each brings them into contact.
Their separate, fragile structures, gradually broken up and compacted by various means, are in time transformed into a solid mass, forming walls of coral rock frequently of enormous extent. The great barrier reef near the northeastern shores of Australia, the longest known, is not less than one thousand two hundred and fifty miles in length.
A LIVING SINGLE CORAL FROM THE PACIFIC OCEAN
The coral polyp is one of the master-builders of the world. It may be likened to a sea-anemone, but is inferior in muscular organism, and immensely superior in defensive organization.
Reef-building polyps do not live below the depth of one hundred or one hundred and twenty feet, and hence require a foundation near the surface. This is supplied by submarine mountains and plateaus, or the slopes of those volcanic cones which form the high islands.
Growing vertically, the reefs repeat at the surface the outlines of their bases, which fact gives rise to the circular figure both of atolls and reefs in mid-ocean, and to the elongated, wall-like form of reefs adjacent to the continents, like those of Florida and of Australia.
Distribution of Corals
Reef-building polyps are confined to the tropical seas, where the winter temperature is not below sixty-eight degrees. Coral formations are most extensive in the Pacific Ocean, especially south of the Equator, and in the two great archipelagoes of the East and West Indies; but a large number of coral islands also occur in the Indian Ocean. The Coral Sea, east of northern Australia, is particularly remarkable for the great extent of its coral reefs.
The Atoll Form of Island
The usual form of coral islands is that of a broken ring, numerous channels affording entrance into the lagoon. Such a group of islands is called an atoll, a Malay term, which has been adopted to designate these singular structures. The central lagoon enclosed by an atoll, is invariably shallow, seldom exceeding a few scores, or at most hundreds, of feet in depth; while the outer sea reaches a depth of thousands of feet at a short distance from the shore, showing that the atoll rests upon a submarine mountain.
Atolls are often clustered together in large numbers, forming extensive archipelagoes. Paumotu, or Low Archipelago, numbers eighty coral islands, nearly all of which are atolls; the Caroline, Gilbert and Marshall islands together contain eighty-four atolls, while the Laccadive and Maldive islands form two long double series of atolls extending eight hundred miles from north to south.
MAP SHOWING COMPARATIVE SIZE OF ISLANDS
(See next page for the Area, Population and Countries to which these islands belong).
ISLANDS OF WESTERN HEMISPHERE
Large illustration (404 kB)
MOST NOTED ISLANDS OF THE WORLD—WESTERN HEMISPHERE
| Name and Sovereignty | Area Square Miles | Popula- tion |
|---|---|---|
| Anticosti (to Britain) | 2,600 | 500 |
| Bahamas (to Britain) | 4,404 | 58,000 |
| Bermudas (to Britain) | 20 | 20,000 |
| Cape Breton (to Britain) | 3,120 | 100,000 |
| Cuba (Independent) | 44,164 | 2,155,000 |
| Dominica (to Britain) | 291 | 35,000 |
| Falkland (to Britain) | 5,500 | 3,250 |
| Feeji, or Feejee (to Britain) | 7,435 | 155,000 |
| Galapagos (to Ecuador) | 2,400 | 400 |
| Greenland (to Denmark) | 46,740 | 15,000 |
| Guadeloupe (to France) | 688 | 182,000 |
| Hawaiian See Sandwich. | ||
| Isla de Pinos (Isle of Pines) (to Spain) | 1,200 | 32,000 |
| Jamaica (to Britain) | 4,200 | 865,000 |
| Long Island (to U. S.) | 1,682 | 2,700,000 |
| Martinique (to France) | 378 | 180,000 |
| New Foundland (to Britain) | 42,734 | 218,000 |
| Porto Rico (to U. S.) | 3,604 | 1,120,000 |
| Prince Edward (to Britain) | 2,184 | 94,000 |
| Santo Domingo (Independent) | 28,250 | 2,700,000 |
| Sandwich or Hawaiian (to U. S.) | 6,449 | 192,000 |
| Staten Island (to U. S.) | 65 | 86,000 |
| Tahiti (to France) | 1,500 | 30,000 |
| Tierra del Fuego (to Argentina) | 18,500 | 1,700 |
| Trinidad (to Britain) | 1,750 | 350,000 |
| Vancouver (to Britain) | 15,937 | 55,000 |
MAP SHOWING COMPARATIVE SIZE OF ISLANDS
ISLANDS OF EASTERN HEMISPHERE
Large illustration (323 kB)
MOST NOTED ISLANDS OF THE WORLD—EASTERN HEMISPHERE
| Name and Sovereignty | Area Square Miles | Popula- tion | |||
|---|---|---|---|---|---|
| Balearic Islands (to Spain) | 1,935 | 326,000 | |||
| Borneo (to Britain and Holland) | 284,000 | 2,000,000 | |||
| Canary Islands (to Spain) | 2,807 | 420,000 | |||
| Candia, or Crete (to Turkey) | 3,365 | 243,000 | |||
| Cape Verde Islands (to Portugal) | 1,480 | 148,000 | |||
| Celebes (to Holland) | 71,470 | 2,000,000 | |||
| Ceylon (to Britain) | 25,332 | 3,595,000 | |||
| Corsica (to France) | 3,378 | 290,000 | |||
| Cyprus (to Britain) | 3,584 | 140,000 | |||
| Elba (to Italy) | 85 | 27,000 | |||
| England (Independent) | 88,729 | 40,835,000 | |||
| Formosa (to Japan) | 13,458 | 3,392,000 | |||
| Gothland (to Sweden) | 1,217 | 56,000 | |||
| Hainan (to China) | 16,000 | 2,000,000 | |||
| Iceland (to Denmark) | 39,756 | 86,000 | |||
| Ireland (to Britain) | 32,360 | 4,382,000 | |||
| Japan | - | Honshiu | 87,485 | 37,415,000 | |
| Khiushiu | 16,840 | 7,727,000 | |||
| Skikoku | 7,031 | 3,290,000 | |||
| Hokkaido (Yezo) | 36,299 | 1,140,000 | |||
| Java (to Holland) | 50,554 | 30,100,000 | |||
| Madagascar (to France) | 227,950 | 2,745,000 | |||
| Madeira Islands (to Portugal) | 314 | 150,600 | |||
| Malta (to Britain) | 117 | 229,000 | |||
| New Guinea See Papua. | |||||
| New Zealand (to Britain) | - | N. Island | 44,468 | 564,000 | |
| S. Island | 58,325 | 445,000 | |||
| Papua, or New Guinea (to Britain, Germany and Holland) | 313,183 | 710,000 | |||
| Philippines (to U. S.) | - | Luzon | 40,969 | 3,800,000 | |
| Mindanao | 36,292 | 500,000 | |||
| Panay | 4,611 | 744,000 | |||
| Cebu | 1,762 | 593,000 | |||
| Leyte | 2,722 | 358,000 | |||
| St. Helena (to Britain) | 47 | 3,520 | |||
| Sakhalin (Japan and Russia) | 29,000 | 30,000 | |||
| Sardinia (to Italy) | 9,306 | 854,000 | |||
| Sicily (to Italy) | 9,935 | 3,685,000 | |||
| Spitzbergen (to Norway) | 27,000 | ... | |||
| Sumatra (to Holland) | 165,000 | 3,200,000 | |||
| Van Diemen, or Tasmania (to Britain) | 26,215 | 197,000 | |||
| Zanzibar (to Britain) | 640 | 115,000 | |||
MARVELS OF THE EARTH’S ROTATION, FORCES AND STRUCTURE
1. Midnight Sun Within the Arctic Circle. 2. The Geyser At Rest. 3. Picture Diagram of a Section through a Volcano like Vesuvius. 4. The Geyser in Action. 5. Section of the Earth’s Crust across France and Italy.
1. Precambrian or Archaean. 2. Cambrian and Ordovician. 3. Silurian. 4. Carboniferous Limestone. 5. Coal Measures. 6. Permian. 7. Trias. 8. Jurassic. 9. Chalk. 10. Tertiary. 11. Volcanic Rocks. 12. Glacial Deposits. 13. Granite. 14. Gneiss. 15. Schist. 16. Alluvium.
Large illustrations: Fig. 2 (left) (272 kB)
Fig. 3 (center) (416 kB)
Fig. 4 (right) (190 kB)
Fig. 5 (bottom) (133 kB)