For the US forces stationed on Baltra during World War II, the Galápagos was about as far from paradise as they could imagine. They called it ‘The Rock’, a wry nod to the infamous prison Alcatraz in San Francisco Bay. When First Lady Eleanor Roosevelt reflected on her morale-boosting visit to the Galápagos in 1944, she acknowledged the backbreaking slog required to establish a military base in such an inhospitable terrain. ‘It is as though the earth had spewed forth rocks of every size and shape and, as one man said, “You remove one rock, only to find two more underneath.”’ For the troops, ‘it must be one of the most discouraging spots in the world’, she wrote. At the same time, however, Mrs Roosevelt could see how this same landscape might grab the attention of those of a scientific bent. ‘To a geologist, I’m sure it would furnish several years of absorbing work.’
The most celebrated visitor to the Galápagos, Charles Darwin, spent only five weeks in the islands, but he’d have gladly spent more. In 1835, Darwin was far more interested in rocks than in living creatures and still believed in the creative powers of God. ‘Geology is a capital science to begin, as it requires nothing but a little reading, thinking & hammering,’ he wrote from his cramped cabin on board HMS Beagle as it lay anchored in the harbour at Lima, Peru. Of what remained of the voyage—across the Pacific and then home to England—it was the prospect of studying the Galápagos rocks that excited him most. ‘I look forward with joy & interest to this . . . for the sake of having a good look at an active Volcano,’ he wrote. ‘Although we have seen Lava in abundance, I have never yet beheld the Crater.’
All this pent-up excitement erupted on the afternoon of 16 September 1835, when HMS Beagle anchored off the north-western tip of San Cristóbal in the east of the archipelago and Darwin had a chance to venture ashore. Although he was clearly thrilled to get his geologist’s hammer out and start tapping away at the rocks, the island’s landscape as a whole was foreboding. ‘A broken field of black basaltic lava, thrown into the most rugged waves, and crossed by great fissures, is everywhere covered by stunted, sunburnt brushwood, which shows little signs of life,’ he wrote in his Journal of Researches. In a rather wonderful passage, he went on to liken the ‘strange Cyclopean scene’ to his native Britain then in the throes of the Industrial Revolution. ‘From the regular form of the many craters, they gave to the country an artificial appearance, which vividly reminded me of those parts of Staffordshire where the great iron-foundries are most numerous.’
The American author Herman Melville, who passed through the Galápagos on board the whaler Acushnet in the early 1840s (a trip that he would draw on for his most famous novel, Moby-Dick), drew upon and embellished Darwin’s account. In The Encantadas, or Enchanted Isles, a series of ten literary sketches of the islands he published in 1854, he wrote, ‘In many places the coast is rock-bound, or, more properly, clinker-bound; tumbled masses of blackish or greenish stuff like the dross of an iron furnace, forming dark clefts and caves here and there, into which a ceaseless sea pours a fury of foam, overhanging them with a swirl of gray, haggard mist, amidst which sail screaming flights of unearthly birds heightening the dismal din.’
FIGURE 1.1 Right, four views of the Galápagos. Philip Gidley King (a midshipman on the Beagle with whom Charles Darwin shared a cramped cabin) made many snapshot-like sketches during the voyage. These drawings, included as engravings in Robert FitzRoy’s Narrative, show Floreana (Charles Island), the approach to San Cristóbal (Chatham Island), a close-up of Freshwater Bay on San Cristóbal, and Isabela (Albemarle Island). Reproduced from Robert FitzRoy, Narrative of the Surveying Voyages of His Majesty’s Ships Adventure and Beagle . . . (London: Henry Colburn, 1839).
Rather interestingly, the very first humans to step on Galápagos rocks had a similar reaction. On 23 February 1535, a galleon set sail from Panama in Central America and headed south. Its mission on behalf of His Sacred Imperial Catholic Majesty King Charles I of Spain was to convey Spain’s head honcho in South America, Bishop of Panama Tomás de Berlanga, to Peru (to check up on the state of play following conquistador Francisco Pizarro’s romp across the continent and the execution of the Incan emperor Atahualpa a few years earlier). The voyage should have taken a couple of weeks at most, but on reaching the equator, the galleon experienced ‘a six-day calm’. Sucked out into the Pacific Ocean on the Panama and Humboldt Currents that merge at the equator, de Berlanga found himself in a cartographic void.
After several days helplessly drifting and with supplies of freshwater running perilously low (‘there was enough water for only two more days’), it looked as though God had forsaken the bishop and his men. But on 10 March, an island—most likely Española in the south-east of the Galápagos archipelago—came into view. Lowering the lifeboat, a party went to search for water and to find grass for the horses on board. They came back disappointed.
Another larger and more mountainous island—probably Floreana—looked more promising, and ‘thinking that, on account of its size and monstrous shape, there could not fail to be rivers and fruits’, de Berlanga set a course for it. When they finally anchored, everyone—including the bishop—staggered ashore desperate for water. Some men set about trying to dig a well, but ‘there came out water saltier than that of the sea’. Others who went inland in search of a spring or stream ‘were not even able to find even a drop of water for two days’. The reluctant explorers became so parched they resorted to tearing apart the cactuses abundant on the lower slopes of most of the Galápagos volcanoes. ‘Although not very tasty, we began to eat of them, and squeeze them to draw all the water from them, and drawn, it looked like slops of lye, and they drank it as if it were rose water.’
Being a good Catholic, the bishop insisted on holding mass to mark Palm Sunday. As far as he was concerned, this act of faith—and the prayers he presumably offered up to his deity—resulted in a group of his men stumbling on freshwater soon afterwards. ‘The Lord deigned that they should find in a ravine among the rocks as much as a hogshead of water, and after they had drawn that, they found more and more.’
Although this island had saved his life, de Berlanga did not give it the most glowing write-up: ‘On the whole island I do not think that there is a place where one might sow a bushel of corn, because most of it is full of very big stones, so much so that it seems as though at some time God had showered stones.’ What earth there is, ‘is like slag, worthless,’ he wrote, anticipating the similarity that Darwin would draw with Britain’s industrialising heartland exactly three hundred years later.
Crack of Doom
The Galápagos landscape owes its striking appearance to the archipelago’s volcanic origins. Darwin’s expectation of seeing an active volcano in the Galápagos was probably raised by exciting accounts of the youngest island—Fernandina—blowing its top a decade earlier.
The American explorer Benjamin Morrell could not have been better placed to witness this dramatic event, sailing his vessel, the Tartar, into Isabela’s Banks Bay on 10 February 1825. As luck would have it, he also had a rather nice way with words. In the middle of the night a few days later, ‘while the stillness of death reigned everywhere around us, our ears were suddenly assailed by a sound that could only be equalled by ten thousand thunders bursting from the air at once; while, at the same instant, the whole hemisphere was lighted up with a horrid glare that might have appalled the stoutest heart!’ he wrote. Less than 20 km away, Fernandina had suddenly ‘broken forth with accumulated vengeance’.
This ‘crack of doom’ soon brought everyone on deck, where the men ‘stood gazing like “sheeted spectres,” speechless and bewildered with astonishment and dismay. The heavens appeared to be in one blaze of fire, intermingled with millions of falling stars and meteors; while the flames shot upward from the peak . . . to the height of at least two thousand feet in the air.’
By about four in the morning, ‘the boiling contents of the tremendous caldron had swollen to the brim, and poured over the edge of the crater in a cataract of liquid fire. A river of melted lava was now seen rushing down the side of the mountain, pursuing a serpentine course to the sea,’ wrote Morrell. The ‘dazzling stream’, he judged, was about a quarter of a mile wide, ‘presenting the appearance of a tremendous torrent of melted iron running from the furnace.’. The ‘flaming river’ broke its banks in several places, sending fiery branches in every direction across the landscape, ‘each rushing downward as if eager to cool its temperament in the deep caverns of the neighbouring ocean’. And when the lava met the water, the uproar was ‘dreadful indeed’. ‘The demon of fire seemed rushing to the embraces of Neptune; . . . The ocean boiled, and roared, and bellowed, as if a civil war had broken out in the Tartarean gulf.’
Morrell had the presence of mind to collect some data, recording the temperature of the sea and air as the drama unfolded. His baseline measurement, taken an hour after the first explosion and before the lava had begun to spill over the rim of the volcano, was fairly typical for the time of year with the water at around 16°C and the night air a balmy 21°C. Some six hours later, with the eruption ‘still continuing with unabated fury’, the temperature of the water had rocketed to an incredible 37°C and the air was now an oppressive 45°C. This was clearly alarming because Morrell and his men were trapped. ‘Not a breath of air was stirring to fill a sail, had we attempted to escape,’ he wrote. By the time the atmosphere had reached an unbearable 50°C, the glue-like resin holding the vessel together had started to run, tar was dripping from the rigging and Morrell and his men were struggling to breathe. Stripping off and jumping into the water would have offered them no respite. At over 40°C, it would have been like diving into a scorching bath.
Thankfully, ‘a breath of a light zephyr from the continent, scarcely perceptible to the cheek’ began to strengthen, and at last Morrell was able to weigh anchor. The wind created a new problem, though, spreading what seemed to be ‘a mass of flame’ north of Fernandina, barring a safe passage into the open Pacific to the west. The only option was to head south in an effort to get upwind of the volcano, and this meant passing within a few kilometres of Fernandina’s molten shoreline.
At the narrowest point, Morrell found the water to be marginally hotter than the air, ‘almost boiling’ at over 60°C. ‘I became apprehensive that I should lose some of my men, as the influence of the heat was so great that several of them were incapable of standing,’ he wrote. The temperatures did ease once they were south of Fernandina, but they pushed on to the safety of Floreana. From there, some 80 km away, Fernandina’s crater still appeared ‘like a colossal beacon-light, shooting its vengeful flames high into the gloomy atmosphere, with a rumbling noise like distant thunder.’
Although Melville didn’t witness anything like the eruption experienced by Morrell and his men, Fernandina clearly got his imagination going. ‘There is dire mischief going on in that upper dark,’ he wrote in the fourth of his ten sketches. ‘There toil the demons of fire, who, at intervals, irradiate the nights with a strange spectral illumination for miles and miles around.’
Given Darwin’s eagerness to see an active volcano in the Galápagos, he probably left a little deflated. The best he managed was a fumarole on neighbouring Isabela, where ‘high up, we saw a small jet of steam issuing from a Crater’. Hardly earth-shattering. But this didn’t stop him taking the first serious look at the geology of these islands. Everything he saw strongly suggested that the landscape was not as static as it might seem at first glance.
Faulting
In South America, Darwin had hit upon the idea that whole chunks of rock had to have been elevated at some time in the past. At his first stop-off in the Galápagos on San Cristóbal, he found an exposed cliff face that contained sandstone and the fossilized remains of limpets, mussels and molluscs. The fact that it was now a couple of feet above the high-tide mark was, he considered, ‘proof of elevation to a small degree within recent times.’ Of course, sea level might have dropped, leaving the marine deposits high and dry, but he thought this less likely.
The most striking example of uplift is at Urbina Bay on the west coast of Isabela. In 1954, a fisherman noticed a white stretch along the shoreline that had not been there before and, upon closer scrutiny, found an eerie landscape strewn with decomposing creatures and an unbearable stench. It’s thought that a single volcanic event caused the ocean floor to rise—almost instantaneously—by around 5 m, exposing some 6 km of reef and stranding sea creatures in the process. There is further evidence of uplift at nearby Punta Espinoza on Fernandina (a projection of lava most likely created in the 1825 eruption witnessed by Morrell), where the tourist landing dock now stands completely out of the water at low tide as a result of a volcanic event in the 1970s.
Such movement of large chunks of rock is made possible by weaknesses, or ‘faults’, in the earth’s crust. Much of the north-east of Santa Cruz appears to have experienced a bit of uplift. In fact, the incredibly flat surface of Baltra (one of the reasons it’s such a good site for an airport runway) suggests it rose up from beneath the sea. The presence of shallow-water marine fossils embedded in the layers of exposed lava on North Seymour and Las Plazas indicates these islets are the results of uplift too.
If there’s uplift, it stands to reason that blocks of crust might also sink. This is harder to demonstrate, but the main town of Puerto Ayora certainly looks as though it’s nestled in a hollow caused by just such subsidence. At the southern edge of town, the footpath towards Tortuga Bay zigzags up a nearly sheer escarpment around 20m high that runs from the north-west to the south-east. From the top, it’s possible to make out a parallel fault line on the far side of town. The land in between seems to have slipped, creating the perfect natural depression for all those houses.
The Rocks
Darwin also paid close attention to the makeup of the rocks, from which he began to infer much about the action of volcanoes. Whilst on Santiago, for instance, he noticed that the rocks on the lower slopes were darker and denser than those at the verdant summit. His explanation was simple. The only way a volcano would throw out lava of different densities, he reasoned, was if it had a large internal chamber of molten rock. This would allow lavas of different composition to emerge in one eruption, the densest near the bottom of the chamber bursting out around the flank of the volcano and the least dense oozing from the top (see Appendix C, Figure 1).
In the course of an eruption, the evacuation of this internal chamber can result in the formation of a caldera, the bowl-shaped depression in the centre of a volcano. The eruption of Fernandina in 1968 caused its magma chamber to collapse and the floor of its caldera to fall more than 200m. It’s not possible to peer into this steaming basin, but the Galápagos National Park does have a tourist trail to the rim of the even larger caldera of Sierra Negra on Isabela.
The emergence of lava from around the periphery of the main vent results in a stunning range of other structures. For the sake of convenience, geologists like to bundle these up into different categories, though in reality small variations in chemical composition, temperature, pressure, eruption rate and the presence of water contribute to a nearly infinite diversity of rocky forms, each sliding imperceptibly into the next. Spatter cones are pretty much as they sound, soft and sticky lumps of lava that fly up into the air and return to earth with a splat, eventually building to leave an irregular cone-shaped blot on the landscape. Cinder cones are similarly explosive but with more gas involved, resulting in solid chunks of pumice-like rock raining down into a reasonably orderly cone. Tuff cones are more regular still, made from fine grains of volcanic ash. Seawater is a crucial ingredient in their formation, another of Darwin’s sleuth-like deductions. If water washes into an open vent, it is transformed to a superhot steam that shoots upwards, flinging minute grains of lava into the air. As anyone who has let sand sift into a pile on the ground knows, these grains pile up into a perfect cone.
Whilst on San Cristóbal, Darwin marvelled at this tormented landscape.
One night I slept on shore on a part of the island, where black truncated cones were extraordinarily numerous: from one small eminence I counted sixty of them, all surmounted by craters more or less perfect. . . . The entire surface of this part of the island seems to have been permeated, like a sieve, by the subterranean vapours: here and there the lava, whilst soft, has been blown into great bubbles; and in other parts, the tops of caverns similarly formed have fallen in, leaving circular pits with steep sides.
Though the particular ‘craterized district’ that Darwin was describing here is out of bounds to tourists, there are lots of other sites where similar structures are visible. There are few better than those glimpsed from the top of Bartolomé, a spot that looks out on one of the most famous and photographed panoramas in the Galápagos. Gazing east, there are the pock-marked remains of several spatter cones. To the west, there are remains of an eroded tuff cone known as Pinnacle Rock. Over the hummock of tuff at the other end of Bartolomé, looking across to the far bigger island of Santiago, there’s a prime example of a cinder cone in the middle distance.
When the lava rolls in a controlled, textbook style towards the sea, it can take on one of two main forms. When there’s a lot of lava and it flows rapidly down the slope, it tends to forms fields of black rubble known as ‘a’ā (a Hawaiian word meaning ‘hurt’ and one of the most useful Scrabble words you’ll come across). When the Galápagos National Park Service (GNPS) began to select its visitor sites, it sensibly avoided fields of ‘a’ā, but it’s pretty much everywhere (as on the steep eastern slopes of Isabela’s Wolf Volcano, for instance).
When the lava is flowing more slowly, it’s more likely to result in rippled sculptures of extraordinary beauty known as pahoehoe (another Hawaiian term, meaning ‘smooth’). One of the best places to see pahoehoe is at Sullivan Bay on Santiago, just across the water from Bartolomé. Darwin saw it on the other side of the island at James Bay. There, between the visitor sites of Espumilla Beach and Puerto Egas, is a vast field of pahoehoe lava, which in places Darwin felt resembled ‘folds of drapery, cables, and . . . the bark of trees’. It’s also in this flow of lava that the Norwegian explorer Thor Heyerdahl found fragments of marmalade jars in 1953. These, he reckoned, had been stashed there by buccaneers in 1683, suggesting the eruption that caused this lava field occurred some years later. This, quipped one witty geologist, is ‘one of the rare uses of marmalade pots in volcano-chronology.’
It’s pahoehoe lava that’s also responsible for leaving tunnels through the landscape. As a thick stream rolls down the slope, the outer layer in contact with the air can form a skin whilst the molten rock continues to run inside. When the flow ceases, it leaves a long and cavernous tube. In the Santa Cruz highlands, there are several farms where it’s possible to walk the length of such lava tubes. One of them runs directly beneath the road between Puerto Ayora and Bellavista.
Weathering
Whilst volcanic activity and faulting can cause nearly instantaneous alterations of the Galápagos landscape, the lapping of waves, the beating of the wind and the occasional deluge result in change on a much longer timescale. In spite of the uplift Darwin had documented on San Cristóbal, he was aware the islands were weathering away. In particular, he noticed the effects that the elements were having on the sandy tuff cones. Of the twenty-eight such cones he took a look at, all of them—without exception—‘had their southern sides either much lower than the other sides, or quite broken down and removed.’ Given the way the elements consistently batter the southern coasts of all islands, ‘this singular uniformity in the broken state of the craters, composed of the soft and yielding tuff, is easily explained,’ he wrote.
The most striking example of this weathering—certainly one that impressed Darwin—is at Tagus Cove on the west coast of Isabela. Indeed, it’s only possible to sail into this popular visitor site because the southern rim of this cone has weathered away to let the sea flow into its centre. When pirates moored their vessels at this spot, their anchors would have been resting on a spot through which lava spewed in the long-distant past. All around the walls of the cove, layer upon layer of lava expose its repetitive and violent volcanic origins.
El León Dormido, or The Sleeping Lion, a popular dive site just off the north shore of San Cristóbal, offers another illustration of weathering. Darwin guessed that the amorphous mass of rock once filled the central hollow of a cone, the sloping walls of which have long since worn away.
FIGURE 1.2. Tagus Cove on Isabela. Darwin figured that this sheltered cove had to be the result of weathering, with the elements battering down the southernmost side of what had once been an intact tuff cone and the sea gradually eating into the core. Reproduced from Charles Darwin, Geological Observations on the Volcanic Islands and Parts of South America Visited During the Voyage of H.M.S. Beagle (New York: D. Appleton and Company, 1891).
FIGURE 1.3. El León Dormido, or The Sleeping Lion, just off the north shore of San Cristóbal is a classic example of weathering. Darwin guessed that the amorphous mass of rock once filled the central hollow of a cone, the sloping walls of which have long since worn away. Reproduced from Charles Darwin, Geological Observations on the Volcanic Islands and Parts of South America Visited During the Voyage of H.M.S. Beagle (New York: D. Appleton and Company, 1891).
Most of Darwin’s explanations for specific geological features hold pretty true. But he went further still, hoping to understand the very underpinnings of the archipelago as a whole. With his living quarters in a corner of the Beagle’s chart room, watching on as the ship’s surveyors got on with mapping out the Galápagos as never before, he was perfectly placed to do so.
With the advantage of satellite imaging, it’s easy to see that Isabela, the largest island in the archipelago, is in fact made up of six neighbouring volcanoes connected by the extent of their laval outpourings. By looking at the Beagle map, Darwin could see this too and reckoned the archipelago’s volcanoes were sitting on a series of parallel lines running diagonally from the north-west to the south-east. This can be most clearly seen on Isabela, where three large volcanoes (now called Wolf, Darwin and Alcedo) are perfectly aligned. With a ruler to hand, it is also possible to draw a parallel line between Darwin Island in the north-west and Española in the south-east, taking in Wolf Island (as opposed to Wolf Volcano on Isabela), Santiago, Santa Cruz and Santa Fé along the way. In addition, Darwin reckoned that Fernandina and Isabela’s Sierra Negra sat on a third parallel, with Pinta, Marchena and San Cristóbal forming a ‘less regular fourth line’.
Darwin also fancied he could see another set of lines perpendicular to the first, linking Floreana and San Cristóbal, for instance, or Cerro Azul, Sierra Negra and Santa Cruz. These interesting patterns, Darwin speculated, might be explained by the existence of rifts on the ocean floor from which lava had blurted and islands had formed. ‘The principal craters appear to lie on the points, where two sets of fissures cross each other,’ he wrote.
The origins of the Galápagos Islands turn out to be a little more complicated than this, but in proposing ‘fissures of eruption’ beneath the waves, Darwin was certainly way ahead of his time. Even a century later, there was considerable opposition to the idea that the earth’s surface was made up of tectonic plates, vast slabs of crust jostling for position as if part of some poorly fitting jigsaw. We have now mapped out these plates in minute detail and are even able to measure their annual drift to within millimetres. The existence of tectonic plates, pushing and pulling in different directions, helps account for so many of the earth’s bizarre geological phenomena, including the Galápagos.
These islands, we now know, sit near the junction of three major tectonic plates: the Pacific Plate to the west, the Cocos Plate to the north and the Nazca Plate to the south (see Appendix C, Figure 2). At the faults between these plates, magma bubbles up from the earth’s mantle, cooling to form new crust and driving the three plates in different directions. At the point where the Pacific Plate meets the Cocos and Nazca Plates, we get the East Pacific Rise; where Cocos meets Nazca we have the Galápagos Rift. But the Galápagos needed more than a couple of rifts spewing out lava to come into existence. Indeed, it would not exist at all were it not for the reckoning of another geological force.
The Hotspot
In 1963, a Canadian geophysicist by the name of Tuzo Wilson published a rather brilliant paper that proposed a new explanation for the origin of the Hawaiian Archipelago. Like the Galápagos, the Hawaiian Islands seem to sit on a straight line, from Big Island in the south-east to Ni’ihau and Kaua’i in the north-west. Until the point that Wilson penned his manuscript, the conventional explanation for this alignment, put forward as recently as 1960, was similar to the one that Darwin proposed for the Galápagos: the Hawaiian Ridge had to be a result of ‘a major fracture in the Earth’s crust through which lava has poured at different centers’.
Wilson had good reason to think this was not how things had happened. There was not the slightest evidence for a fault beneath Hawaii—or, for that matter, beneath any of the other island chains across the Pacific. Even if there were such much mooted cracks in the ocean floor, they could not explain why Hawaii aged from east to west, its islands lined up like schoolchildren in a playground, with the oldest at the western extreme and the youngest, most active volcano to the east.
Wilson had a much better idea. In his paper, he did not refer to ‘hotspots’ but talked of ‘sources of lava’ originating deep within the earth’s core. If the Pacific Plate were moving steadily, rather like a conveyor belt, in a north-westerly direction over such a powerful source, it would explain the extraordinarily linear arrangement of the islands. ‘Each volcano, as it was carried away from its source, slowly became inactive,’ he envisaged. ‘The farther a volcano is from the East Pacific Rise, the older it is. The longer a chain, the older is the chain.’ Rather wonderfully, the idea of a single, powerful hotspot also explains why Hawaii doesn’t really stop at Ni’ihau and Kaua’i. In fact, it would be best to think of the Hawaiian Islands as the exposed peaks of a vast submarine mountain range, the Emperor Seamount Chain, that extends for thousands of kilometres into the Pacific.
The Galápagos Islands, we now know, are fired up by one of Wilson’s ‘sources of lava’, a deep-seated hotspot that periodically sends volcanoes bubbling to the surface of the Nazca Plate. In contrast to the Pacific Plate (on which Hawaii sits), this slab of crust is conveying these eruptions off to the east rather than the west (courtesy of the combined forces of the East Pacific Rise and the Galápagos Rift). So, as in Hawaii, the islands we call the Galápagos are just the manifest pinnacles of a much longer mountain range known as the Carnegie Ridge. Of the volcanoes that do still peak through the waves, those closest to the hotspot in the west are the youngest, highest and most active (like Fernandina and Isabela’s Cerro Azul, whose oldest lava flows date to some 500,000 years ago), and those furthest from the hotspot in the east are the oldest, lowest and least active (San Cristóbal and Española, appearing somewhere between 3 and 4 million years ago). See Appendix C, Figure 3.
Interestingly, there is another submerged mountain range, the Cocos Ridge, that stretches from the Galápagos region to the north-east all the way to Panama. The existence of this second blurted sequence of volcanoes suggests that the Galápagos hotspot once sat closer to the Galápagos Rift and perhaps even beneath the Cocos Plate itself.
It also suggests that at their eruptive genesis, these now submerged mountains probably broke through the surface just as Fernandina does today. As they were carried away from the hotspot, they cooled, contracted, eroded and returned beneath the waves, no longer bona fide, above board islands but submarine ones known as ‘seamounts’. Studies that have taken a closer look at the Carnegie and Cocos Ridges have found their geology to be similar to that of today’s Galápagos, indicating they were probably borne from the same hotspot. Other work has even found evidence to support the idea they were once real islands. Many of the seamounts have flat tops, most likely smoothed by the weathering action of wind and rain. Others are covered with cobble-like stones thought to have been caused by the gentle lapping of waves. Some contain mollusc-bearing limestone, deposits that are probably the remains of beaches long since lost.
This is more than just an interesting aside. It means that the islands we have come to know as the Galápagos will, one day, recede beneath the waves. First Española, then San Cristóbal and so on from east to west, each assuming a monumental position on the undersea Carnegie Ridge. But it’s unlikely the Galápagos flora and fauna will sink with them. For the hotspot will, by then, have churned out new islands, naked slopes eager to be clothed by the plants and animals on the islands to their east.
As we shall see, this process of succession is crucial to the understanding of the Galápagos. In many instances, the ancestors of modern Galápagos species have been island hopping for millions of years. The current islands are merely the temporary homes of these highly evolved and much prized species. In the future, their descendants will have colonised islands that are, as yet, but a twinkling in the Galápagos hotspot’s fire-filled eye.
