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The Best Adventure and Exploration Stories Ever Told

Page 27

by Stephen Brennan


  By reading Lyell, Darwin at least had ended, for himself, his paleontological nonsense, and yet at that time no one had worked out a satisfactory explanation of the origin of life. Not that others had not questioned a teleological concept of life’s genesis. Erasmus Darwin, for one, grandfather of Charles and a writer in the gay science, had in his poems on nature sowed many an evolutionary seed; M. Lamarck, the ill-used, blind French former soldier who became a leading zoologist, had suggested mutations in species; and in America, as early as 1832, Samuel Constantine Rafinesque-Schmalz had suggested the “great universal law of perpetual mutability”; yet none of these precursors of evolution had worked out a system to explain the origin of species. Most everyone then believed in the divinity of man, everyone presumed that “species” were created especially by God, and Darwin was a man of his time.

  H.M.S. Beagle put into Brazil, and Darwin walked in the magic jungles of that magical land; then the Beagle sailed to Argentina, and he collected specimens on the tortilla-flat pampas. Aboard the Beagle he sailed to Tierra del Fuego and wandered over the tundra of the land of fire, observing, collecting, and thinking of the material he was piling up in his chests aboard the Beagle. After a visit to the Falklands, and a return again to the pampas, he was suddenly struck with the first shaft of evolution. In a reddish clay bank of the great pampean formation of Punta Alta in Patagonia, Darwin had fallen upon an ossuary of lost world mammals. In his own words he had found a “perfect catacomb of extinct races.” To his great surprise he found fossils of animals that much resembled the animals he now saw in the pampas of jungle of South America. Fossils above all were time indicators of geological progression, and, more, they were indications that the present species that roamed the South American earth evolved from these historic forms. Darwin did not put these thoughts in so many words, yet these fossil discoveries started a whole chain of new thinking. The Beagle next sailed into the halcyon Pacific, continuing its survey, and Darwin scrambled among the rock hard Andes, chipping off bits of the South American Andes for future study, and while the Beagle stayed at sea, incessantly, ceaselessly sounding and mapping, Darwin, on horseback, explored the coast line of Chile.

  Following the cold Humboldt Current, they came to Peru, and there Darwin debarked for a glance at Lima; then on a day notable in the annals of man, the Beagle shaped its course for the Enchanted Islands.

  On September 15, 1835, the Beagle made the landfall of Chatham Island, Galápagos.

  Charles Darwin found the Galápagos quite different from Herman Melville’s poetical explanation, as “five and twenty heaps of cinders.” Actually the islands were a vast volcanic archipelago scattered over 23,000 square miles of water, although comprising islands whose total land area was a little less than 2,800 square miles (more than half of which was contained in the largest island, Albemarle). An islandic enchantment that was contained between latitudes one degree north to two degrees south, and between the longitudes eighty-nine degrees to ninety-two degrees, the Galápagos were 600 miles directly west of South America and cut by the Equator (it passes through the northern tip of Albemarle). Albemarle Isle, 75 mile in length, 40 miles at its widest, was at places 5,000 feet high; there are craters of five huge volcanoes, two of which are still active; and Narborough, the next island in size and volcanically intensely active, lies “in the black jaws of Albemarle like a wolf ’s red tongue in his open mouth.” A great hulk of clinker, its slopes are blackened and smoldering by the banked fires of the volcano. Next in size in the archipelago is Indefatigable, which lies in the vortex of the islands. It—although pictured on the maps as having a single central cone—has in fact several craters, and its cactus-studded littoral is a veritable citadel.

  James Island, where Darwin spent much time, next in size and historical importance, is northwest of Indefatigable and in the shadow of giant Albemarle; it consists of two primary volcanoes, the larger 1,700 feet high, forming the main mass of the island; but scattered about its surface are many small parasitic cones. Farther north, detached from the main group is Tower Isle, a low, flat, extinct crater, broken down by erosion into a gigantic bay; then there is Bindloe, again dominated by a single crater, and near to it Abingdon, studded with volcanic craters, one of which was spewing out its lava not long since. And south of the enchanted vortex, other islands—Barrington, a small, many coned island, not more than 900 feet in altitude, with a fine small harbor and—a rare phenomenon in the Galápagos—a dry watercourse cutting through the lava clinkers leading to the bay; and west of Barrington, Chatham Isle. Shaped like a shriveled appendix, 9 miles wide and 20 in length, with many extinct craters—one of which is 2,630 feet high—Chatham Island is the most important in the group, and the reason: water. On the lee side of the island, Fresh Water Bay; on the weather side, Wreck Bay, port of call of the Galápagos and now for a century its nominal capital. Water, gathering in one of the high, broken-down craters, from rain and the heavy mist, is offered here, alone in the whole archipelago, in continuous supply. Then south of this island is Hood, flat Hood—only 600 feet in altitude at its highest part—burnt out and arid and waterless. Directly south of the center is the most famous island in the enchanted archipelago—Charles Island—scene of the first informal post office of the whalers, the “Dog Kingdom” of General José Villamil, the first one to be inhabited of the whole group, and in the century the locale of the sensational murder of the Baroness, “Queen of the Galápagos.”

  Although Charles Island is a mere 9 miles in diameter and 1,780 feet in height, its central craters are broken down, reduced to a circle of eroded hills that mark the site of the first settlements. Its black lava fields are severely weathered into rich black volcanic soil which is found between the interstices of huge ironhard lava boulders. The surfaces behind Post Office Bay have been reduced by time and weathering to broken masses of scoriaceous material. Young Darwin, looking over the irregular masses of lava, believed that the islands were built up by centuries of eruption from the bottom of the sea. He gradually came to feel that the islands received their inhabitants and their flora from the casual drift of sea and wind; in this he was backed by Alfred Russel Wallace. And geology now supports Charles Darwin.

  “Under the east Central Pacific there lies a vast area,” writes L.J. Chubb, who himself crawled over the Galápagos terrain to make his observations, “the Albatross Plateau under depths of less than 2,000 fathoms. . . . No islands rise from the central part of the plateau, but at each end is an archipelago that appears to have been built up on a set of intersecting fissures. The Marquesas at the western end, and the Galápagos at the eastern. On or near its southern margin, too, there are several volcanic islands, including the Mangareva, Pitcairn, Easter, Sala-y-Gomez and the Juan Fernandez Islands.” What does this suggest? That this great oceanic subterranean plateau is a resistant block and that internal pressure has cracked and fissured at its ends under the sea at the Galápagos, Easter, and Juan Fernández Islands and the plateau has become cracked and fissured “and that on the fissures volcanic islands have been erected.”

  Although definite geological analysis of the formation of the Galápagos is missing because the islands—purely volcanic—possess no fossils, they are believed to have been built up during the early Pleistocene period in this manner: first, a period of major eruptions when the great volcanic cones were built up; second, minor eruptions, when parasitic craters were created; and third, a welling up of lava from the broken fissures, which, rolling downward, coalesced with the outpourings of volcanoes and grew, thus, into larger land masses. There is no doubt, as the geological evidence suggests, that the origin of Juan Fernández—miles to the south of the Galápagos and the Marquesas,—miles to the west—is the same as the Enchanted Isles. And there is one other important fact that must be stressed, since it bears not alone on Darwin’s theories of evolution but on the coming of animals to the islands. To Darwin, the Galápagos were of pelagic origin— purely oceanic, without continental land bridge; and in t
his, too, he has been confirmed by a modern geologist who writes that the Galápagos “show some evidence of elevation, but very little of subsidence.” In 1892, Darwin had been challenged by Dr. George Baur: the Galápagos, he said, were continental islands, the tops of mountains formerly connected to the mainland by a land bridge, which sank, isolating the fauna— the Galápagos were, he wrote, “islands of subsidence.” This theory—without oceanographic evidence—was popularized by William Beebe in his Galápagos, World’s End, by an oceanographic map actually purporting to show the Galápagos connected with Cocos Island in this islandic firmament and attached to Central America. Most of the evidence—but not all—now points to the Galápagos’ being wholly oceanic in origin. Still the fight between pelagicisists and subsidenists goes on.

  What then of the climate of these equatorial islands? Why, Darwin at first asked, were they like a desert? Since they were adjacent to the tropical shores of Ecuador, why did they not have the huge ceibas, draped with trailing lianas, and other tropical verdure? What had he expected? Well, at least, to see palm trees and gaudy-colored birds, to hear the raucous screech of parrots. Instead, he found desert shores with leafless, squat bushes, cactus, and myriads of dully-colored birds. Darwin had come to the Galápagos in the dry season. In the rainy season—December, January, February, and March—when rains deluge the Galápagoan landscape, all of these dead things come to life. That Darwin did not see. Contrary to first impressions, the islands receive quite an amount of water. One of the Danish settlers long resident on Indefatigable Island, calculated that in the month of January he had collected from the 630-foot-square corrugated roof which covered his dwelling one hundred gallons of water. This fall—mostly heavy mist—increased until April, the beginning of the dry season. Where did this water come from? Why, from the garua, a constant falling mist that was but a consequence of the cool current which enveloped the Galápagos.

  There, too, is a vast difference in the Galápagos between the lower dry and the upper moist zones. On the islands of greater altitude which receive the westerly balm of garua, the vegetation is green and the earth a thick loam. This moist zone differs, as Darwin soon found, on each island. The westernmost islands—Charles and Chatham (possibly the oldest in the archipelago)—receive the greatest amount of the garua, and here erosion and weathering have progressed farther than on all the other islands. Yet on most of the larger islands—Indefatigable, Albemarle, and James—above six hundred feet altitude one stumbles across earth and thick-trunked trees which have, however, no great height since they, unable to sink their roots beyond a three foot depth because of the impenetrable lava, fall on their sides.

  At higher altitudes there are grass, vines, and, in some areas, orchids. When one reaches the highest parts, it is cold and misty, the land covered with soil and verdure, and all of the desert character one ascribes to the Galápagos is lost. Here they look something like the parámos of the Andes at eleven thousand feet of altitude.

  Yet why are the Galápagos not tropical islands? The answer lies in the vortex of currents which surround the islands and give them their patronymic, the Enchanted Isles; and the cause is the Peruvian coastal current, better known as the Humboldt Current.

  The Galápagos Island are the oceanic terminus, more or less, of a titanic current, which, in effect, is the opposite of the Gulf Stream. Whereas the Gulf Stream, originating in the Caribbean , sweeps across the Atlantic to the British Isles creating an unusual warmth for northern latitudes, the Humboldt Current brings cool atmosphere to South America’s western coast and turns a land which would be naturally tropical into a desert littoral. The current turns at the tip of South America and moves northward at considerable speed. In this wide current, whose coolness is the result of an upwelling of cold water and “wind acting in conjunction with forces due to the earth’s rotation,” the water is thus many degrees colder than the atmosphere. This current, too, is the reason that rain does not fall on the whole coast of Chile and Peru. The positions between sea and land are reversed. When the air from the current rolls over the land, its temperature is raised instead of being lowered. Instead of condensation, absorption occurs. Rain does not fall, except under unusual climatic conditions, in Chile or Peru.

  The current rolling northward up to Cape Blanco, just below the Bay of Guayaquil, turns abruptly and pursues a west-northwest course outwards toward the Galapagos Islands. There the current bathes the equatorial islands in cold water, modifying and changing the tropical temperature. Then, to complicate matters, there is another current—a warm current moving southward to the Equator—that converges in the months of December, January, and February with the cold Humboldt. It is known as El Niño, “The Child,” for it comes near Christmas time and the birth of the Christ child. Warmer, and reduced in salinity, El Niño bathes the Ecuador littoral with its tropic waters, and the country opposite is clothed in luxuriant forests. It mixes with the Humboldt, Galápagos-bound, causing rain to fall on the isles, and the whole sea is churned by irregular currents and complex eddies. This was the current that dragged the ship of Tomás de Berlanga, in 1535, to the islands; this was the current that made Diego Rivadeneira believe them enchanted; this was the current which was to cause many a death in the future. It created the paradoxical geographical climate of the islands, and it also brought the animals.

  The most famous inhabitant of the islands is the galápago, the giant land tortoise after which the islands were named. Darwin, who made the first zoological description of them, saw the tortoises on James Island on October 9, 1835; “In the pathway many tortoises were travelling to the water & others returning, having drunk their fill. The effect is very comical in seeing these huge creatures with outstretched neck so deliberately pacing onwards. I think they march at the rate of 360 yards in an hour; perhaps four miles in the 24.” So Darwin began the scientific investigation of the galápago. He did not know then that there were fifteen species of galápago in the archipelago, that each island had a species peculiar to it. And what tortoises! “None of your school-boy mud-turtles,” as Herman Melville wrote, “but as black as a widow’s weeds, heavy as chests of plate, with vast shells, medallioned and orbed like shields, dented and blistered that have breasted a battle—shaggy, too, here and there, with dark green moss, and slimy with the spray of the sea.” Huge tortoises they are, five and one-half feet in measurement across the arc of the plastron—lost-world creatures roaming lost-world islands.

  During the Tertiary times, sixty million years ago, a Chelonian type of gigantic tortoise was well distributed in the northern hemisphere; fossils of it are found in our South-west in Patagonia, and in the island of Cuba. There is a mounted specimen of a fossil tortoise from India in the American Museum of Natural History. When alive, it weighed approximately 2,100 pounds! America was the home of the earliest known land tortoise, and curiously enough, the great fossil from India most closely resembles the extinct American species. At one time, in the lush period of the age of reptiles, immense tortoises covered the earth. Rapacious mammals then appeared, and later, man. Faced by these two competitors, the giant tortoises rapidly disappeared. After millions of years of existence they became extinct everywhere except on two spots of the globe: the islands of the Aldabran group (Seychelles, Reunion, Mauritius) in the Indian Ocean and the Galápagos Islands. Yet both of these island groups are remote and isolated from any large land masses and were unknown to either four-footed mammal or two-legged man. The tortoise-bearing islands being far out from land, it can hardly be said that the tortoises, aware of such islands, made for them purposely. There must be some satisfactory way to explain the presence of these animals on islands hundreds of miles off the mainland. Yet it has not been explained. Charles Darwin’s phrase “how easily explained” scarcely suffices. It remains a mystery.

  Round and hard, in excellent mimicry of a billiard ball, both in size and appearance, the eggs (there are usually twenty in a cache) are buried by the mother tortoise fifteen inches or more deep in the d
ry rubble-like soil of the islands. After two months of incubation the tortoise breaks the egg shell and begins the fight to break through the hypogeum where it is confined. In its egg, the little galápago is folded over like a jelly roll, its small head bent over to touch its tail. The shell is soft, although already etched on it is a design of thirteen symmetrical five-sided plates. It weighs two ounces and is, when unrolled, no more than two inches in length. Now begins the exodus. It has to dig itself out of the nest below. The ground is loosely packed, but the animal’s progress upward is stopped by the hard earth crust. The young tortoise is then extremely delicate, the shell is not yet hardened; to push aside hard-packed earth is Herculean labor for a thing so newly hatched. Egg caches have been found in which some of the young tortoises had escaped from the eggs, but had died before they could get out of the hole. The tortoises on the bottom have the most difficulty. The age-old struggle for existence is fully exemplified in this microcosm of the tortoise world.

  When it is free of the hypogeum, the tortoise walks about dragging a tough egg yolk sac about the size of a half dollar, which adheres to the ventral or underside of its shell, attached like a placenta. The young tortoise drags this about until it has absorbed the whole of it into its body; it does not, it is believed, eat other food so long as the placenta is being absorbed, and this takes from six to ten days. Then the ventral portions of the soft plastron close and the tortoise is ready to begin its life cycle. At this time it weighs not more than two and one-half ounces; Galápagos tortoises, fully grown, have actually been found to be heavier than five hundred pounds. One may picture the difference, the disparagement between two ounces and five hundred pounds. Few animals exist that exhibit such a tremendous increase in size, an increase of four thousand times the original weight.

 

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