During his Antarctic expeditions, Shackleton left a volcanic legacy by overseeing the first exploration of Mount Erebus. But in his reports he notes an indication of another volcano, one which has never been identified. In this post I propose the first identification of this mystery volcano.
Each their own. The three most famous explorers of Antarctica are Amundsen, Scott, and Shackleton. Amundsen the victor: the first person to reach the South Pole and return in safety. Scott the tragic hero: the first person to reach the South Pole and not return. And Shackleton, failing to reach the South Pole on three different attempts, but returning safely against impossible odds. On his first attempt, in 1902 with Scott and Wilson, he reached 82 degrees south. The second time, in 1908, he came very close, at 88 degrees south, a little over 100 miles from the Pole. On this expedition, Antarctica’s most active volcano, Mount Erebus, was climbed for the first time. On his third attempt, he never even set foot on the continent, and lost his ship in the pack ice. But this failure became his most inspirational journey.
Sir Ernest Shackleton’s third expedition left England Aug 1, 1914, within hours of the outbreak of the first world war. The aim of the expedition was to land along the Weddell Sea and to march across Antarctica via the South Pole to the Ross Sea. After a stop-over in South Georgia, Shackleton managed to reach the Weddell Sea, but the sea ice was far heavier than expected and he failed to find a way through. We now know that the south-east part of the Weddell Sea collects a mass of ice every 3-4 years, as it gyrates clockwise around the sea: Shackleton happened to hit one of those years. After discarding a promising landing site, his ship the Endurance became stuck in February 1915 and froze into the sea ice. Many months of drifting with the ice pack followed. A BBC article shows photographs of this time, bringing the characters vividly to life.
On October 27 the ship finally succumbed to the pressure and was crushed; the wreckage sank on November 21. Shackleton and his crew set up camp on the ice. Only three small lifeboats were left. The camp drifted north with the sea ice, which by March had become so thin that one person started to feel sea sick from the swell. On April 9, 1916, the ice finally broke up. The ship-wrecked crew managed to launch the small boats just before the ice disintegrated. Neither the small boats nor their crew could handle the swell of the open ocean: the soaked man were suffering from hypothermia and frostbite. But hiding between the ice floes was equally dangerous. After a week of this, near death, they managed to reach Elephant Island, a desolate and unforgiving place without food or shelter. Shackleton and four companions left to get help, in one of the greatest sea crossings ever recorded. In a small lifeboat with a flimsy covering, they covered 800 miles to South Georgia, across the most tempestal ocean on Earth, at the end losing their mast in a hurricane which (unbeknown to them) sank a large ship nearby. Their navigation, based on four difficult sextant measurements during the two week journey, is legendary. Out of fresh water and without mast, by necessity they landed on the wrong side of South Georgia. Waiting for a full moon, three man managed to cross South Georgia on foot, a feat never achieved before. This journey over unexplored and unmapped mountain ranges took 36 sleepless hours, during which they almost froze to death. Shackleton and his two companions finally reached the Norwegian Stromness whaling camp, just before a snow storm started which they could not have survived in the open. The first people to see the three ruffians ran away in fear!
It took four more months before the crew members on Elephant Island could be rescued by the Chilean navy, on the day their food supplies ran out. Amazingly, everyone survived. In a world racked by war and desperate for good news, this story of impossible survival went viral. Shackleton overcame disaster, mutiny, and anything the Antarctic threw at him, while keeping his man (including a young stow-away) safe. A world at war badly needed such an image.
Shackleton’s book about the ‘worst journey in the world’, simply called ‘South’, is a gripping read. It leaves out some less convenient details, such as the stow-away and the mutiny, but exudes a sense of optimism in every situation. It also contains a wealth of scientific observations, regarding the weather, the ice, and even the first recording of an oceanic super-wave during the desperate race to South Georgia.
One of these observations caught my attention. Shortly after reaching the Weddell Sea, Shackleton writes
“We passed at least two hundred bergs during the day, and we noticed large masses of hummocky bay ice and ice foot. One floe of bay ice had black earth on it, apparently basaltic in origin, and there was a large berg with a broad band of yellowish brown right through it. The stain may have been volcanic dust.”
This happened on Jan 2, 1915, before the Endurance had become stuck. The location was near 69o 49′ South, 15o 42′ West.
The description of the yellow-brown band sounds very much like a volcanic deposit, as Shackleton identified them. Such layers are fairly common in icebergs around Iceland (albeit mainly black rather than yellow.) The dark basaltic earth may have come from the same eruption, perhaps dropped on the floe by a disintegrating iceberg, but it may be unrelated. Ash does not travel very far and the iceberg must have been fairly close to the erupting volcano. The fact that the yellow-brown band was within an iceberg suggests that the iceberg had not yet become a traveler but was still growing at the time of the eruption. Most likely it was part of one of the many Weddell Sea ice shelves. An ice shelf is a floating or grounded extension of a land glacier, which remains in place year round, and can be many hundreds of meters thick. The broadness of the volcanic band may mean that the eruption lasted some time, but also indicates that there was limited compression by the weight of snow from later years. The eruption could have been some years or decades before the iceberg calved, but probably not centuries or the band would have become thin layers of ice.
The Weddell sea is known for its gyre. Ice moves around with the ocean currents in a great circle, following the coast east to west, bending north, and returning west to east. The iceberg could have formed somewhere along this gyre. The drift of the Endurance also followed the gyre. If an iceberg fails to escape, the gyre will return it to the Antarctic coast east of the Weddell Sea where it will go round once more.
There are many volcanoes in the region, mainly along an arc stretching from the sub-Antarctic South Sandwich Islands to the Antarctic Peninsula. A list of Antarctic volcanoes, and a separate list of those of the South Sandwich island, is available on wikipedia. But which of these could have been Shackleton’s culprit? Volcanic activity is poorly recorded in this area, where few people are present at the best of times (and none outside of the summer season) and the weather is often far from ideal for eruption viewing. Still, it seems that there are a number of highly active volcanoes in the area, vying with the frequently erupting Mount Erebus on the other side of Antarctica. Mount Michael on the South Sandwich islands erupted during 2015.
Which volcano could have caused Shackleton’s yellow ice band? Can we solve this mystery of the lost volcano? Even if Shackleton failed to reach the hidden continent, the discovery of volcanic activity could still return a scientific success.
One possibility is the most active volcano in the region, Deception Island, with documented eruptions in 1842 and 1906, and suggestions of further, undetected eruptions in between. Deception Island has had a massive caldera-forming eruption in the distant past, but recent eruptions have been small, with eruption volumes around 0.05 cubic kilometer. It is located on the other (western) side of the Antarctic peninsula. The prevailing wind over the peninsula is westerly, which is in the right direction to carry the ejecta across the peninsula to the Weddell Sea. The largest ice sheet there is the Larsen C Ice Shelf, but at 300 kilometer distance it seems much too far and it is in the wrong direction for significant deposits. Further north are three smaller ice shelfs: Larsen B, Larsen A and Prince Gustav, where the latter two may have been connected in Shackleton’s time. The Larsen A and Prince Gustaf ice shelfs disintegrated in 1995 and no longer exist, early victims of the current warming in the region: the Antarctic Peninsula has warmed by 2.5C since 1950, possibly the fastest rate on Earth. Larsen B partially collapsed in 2002 and is expected to be completely gone by 2020. Larsen A/Prince Gustav was a small, fast moving ice sheet before its collapse and is a plausible candidate for Shackleton’s iceberg. Prince Gustav is less than 100 kilometer SSE from Deception Island but this is still rather far for deposits from a smallish eruption.
There are also volcanoes on the Weddell Sea side, which are located much closer to the Prince Gustav shelf. The closest is James Ross Island, next to the ice shelf, which contains a large shield volcano, but no historic eruptions have been recorded.
The Seal Nunataks are a group of 16 small islands of which Robertson Island is by far the largest, located within the historic area of the Larsen A shelf. They were discovered by Captain Carl Larsen, a Norwegian whaler, on December 11, 1893, and at that time it was noted that Lindenburg Island and possibly Christensen island were in a state of eruption. Lindenberg was said to have a black ash flow, and Christensen island to show fumaroles. These observations have been questioned but in the 1980’s the Nunataks were indeed confirmed as volcanic: evidence for very recent eruptions on Lindenberg and Dallman (but not Christensen) gave credence to Larsen’s observations. Murdoch island had an eruption around 1982 which spread ash around much of the surrounding ice. Based on the location and the date, the 1893 eruption of Lindenburg Island is an excellent candidate for Shackleton’s volcanic iceberg deposits.
An interesting coincidence is that Larsen, like Shackleton, once lost his ship: in 1903 his ship was caught in the ice and sank, leaving him marooned on Paulet island for the winter. Larsen eventually managed to lead all but one of his stranded crew to safety. Paulet is a volcanic island on the Antarctic Peninsula, kept ice-free by geothermal activity; during his ice drift Shackleton came within 100 kilometer of Paulet island and tried to march there, but gave up when pulling the boats across the ice proved too difficult. Shackleton also considered sailing for Deception Island for rescue. In Antarctica, all stories are connected.
Deception Island is less likely due to its distance from the ice shelfs and the lack of a reported eruption of the right age. The most plausible origin of the volcanic stains seen by Shackleton is the December 1893 eruption of Lindenberg Island, with the iceberg originating from the Larsen A or B ice shelf. This could also explain the basaltic ash which could not have traveled far from the eruption site. The deposits stayed in the ice shelf for 20 years before calving in the southern summer of 1914. The Larsen B shelf, before its collapse, was measured by J. Wuite to move at 1-1.5 meter per day near the Seal Nunataks, or about 0.5 km per year. Larsen A may have been similar or a bit faster. Lindenberg Island was no more than 20 kilometer from the edge of the Larsen A shelf. Westerly winds would have spread the deposits from the volcano towards the edge of the shelf: the volcanic deposits would been released into the Weddell Sea over a period of some 40 years. A 20 year ‘shelf life’ is therefore reasonable. Calving in early 1914 started the icebergs with their volcanic legacy on their journey through the Weddell Sea gyre. They failed to escape the gyre, and encountered Shackleton a year later, part of the dense ice which soon after stranded the ill-fated expedition.
Shackleton died in 1922 of heart failure, on his fourth journey to Antarctica. He left us with inspiring stories, and many valuable observations. And now, perhaps, a second volcano can be added to his legacy.
More information and sources of information
South! Shackleton’s expedition book, available through Gutenberg
Recording made by Shackleton in 1910
Wuiten et al: Evolution of surface velocities and ice discharge of Larsen B outlet glaciers from 1995 to 2013. Published in The Cryosphere, 9, 957-969, 2015
The Seal Nunataks: An active volcanic group on the Larsen Ice Shelf, West Antarctica, O. Gonzalez-Ferran, published in Antarctic Earth Science, fourth international symposium, Adelaide 1983, p. 334-337
Shackleton’s trans-Antarctica expedition
Jan Mayen: volcano in the freezer
THEY, weary, wayworn, and sleep- less, through the long withering night. Grimly clung to your iron sides till with laggard Dawn came the light: Both heart and brain upheld them, till the long-drawn strain was o'er, Victors then on your crown they stood and gazed at the Western Shore; The distant glory of that land in broad splen- dour lay unrolled. With icefield, cape, and mountain height, flame rose in a sea of gold. Oh! Herald of returning Suns to the waiting lands below; Beacon to their home-seeking feet, far across the Southern snow; In the Northland, in the years to be, pale Winter's first white sign Will turn again their thoughts to thee, and the glamour that is thine. (AURORA AUSTRALIS BY E.H. SHACKLETON)