Travels in geology: Antarctica: Following in the footsteps of giants
John Van Hoesen
John Van Hoesen
John Van Hoesen
John Van Hoesen
In fall 2012, when I told friends and colleagues that I was heading south for a few weeks, they assumed that I, like many other northeasterners, was going to Florida or the Bahamas for a break from winter weather. Instead, I was headed to the iciest and southernmost place on Earth: Antarctica.
My fascination with cold, remote places was initially sparked by Barry Lopez’s “Arctic Dreams,” and stories of the Franklin Expedition and Admiral Peary in the Arctic fanned those sparks into flames. So when I read an announcement for a field trip to Antarctica and the Scotia Arc, sponsored by the Geological Society of America (GSA) and the Jackson School of Geosciences at the University of Texas at Austin, and adeptly guided by Cheesemans’ Ecology Safaris, I signed up immediately.
Thus began almost 11 months of preparation and planning — including everything from researching and buying the right clothing to figuring out how to avoid sea sickness. Little did I know that I’d soon be visiting remarkable type localities and walking where famed explorers like James Cook, Charles Darwin, James Clark Ross and Ernest Shackleton once walked.
The 26-day field trip raised the curtain on a year-long celebration for the 125th anniversary of the founding of GSA, and also raised the bar for any future geology trip I might take.
First Stop:The Falkland Islands
The trip began on Dec. 26, 2012, with me and the almost 100 other geologists and participants making our way to Santiago, Chile. From there, we flew about five hours to the Falkland Islands, the first stop on the field trip.
Once we landed, we boarded a bus and followed Darwin Road en route to a two-day tour of this fascinating geologic region.
The Falklands record both the initial fragmentation of the Gondwana supercontinent about 400 million years ago and expose the approximately 300-million-year-old Fitzroy Tillite, representing the Late Carboniferous to Early Permian glaciation of Gondwana. This formation is named after Captain FitzRoy of the HMS Beagle and correlates with the more famous Dwyka Group of South Africa.
But perhaps the most interesting geologic features — described in detail by Darwin — are the sinuous scars slashing across the Bluegrass-dominated grasslands, the famous stone runs of the Falklands. These periglacial block fields are composed of resistant quartzite boulders from the Late Devonian Port Stanley Formation. I think many of us would have liked to wander and explore the stone runs for the rest of the day, stepping over the same ground that Darwin covered, but we needed to keep moving.
Where Darwin Drive ends, Ross Road, named after Sir James Clark Ross, the British explorer who captained the HMS Erebus through many uncharted Antarctic waters in the 19th century, begins. This was a fitting transition, as we were heading into Port Stanley to board our expedition vessel, the Akademik Ioffe. The ship was modernized and equipped with state-of-the-art technology, but as we left terra firma and boarded what would be our floating home for the next few weeks, I couldn’t help but think about the perilous expeditions of those before me, including the 2007 sinking of the M/S Explorer. The Explorer was on a cruise following Shackleton’s route that ended when the ship hit an iceberg and the 100 passengers and crew had to be rescued.
Southward to the Scotia Arc
Leaving the Falklands, we sailed south across the Circum-Antarctic Current into the Scotia Arc, a unique tectonic setting and a veritable playground for geologists.
The Scotia Arc, a group of remote islands, is bounded to the north and south by transform boundaries where the Scotia Plate grinds against the South American and Antarctica plates. The western edge is defined by the Shackleton Fracture Zone and the eastern edge is defined by the South Sandwich microplate and the East Scotia spreading ridge.
These geometries are primarily driven by different rates of apparent westward migration — relative to Africa — of the South American and Antarctic plates. The migration started during the Early Eocene with the opening of the Drake Passage following the separation of South America and Antarctica. And the continued separation and development of left-lateral motion spawned the smaller South Orkney and South Georgia microcontinents, visible today as islands.
Western South Georgia Island
South Georgia is an absolutely stunning island fringed with forbidding cliffs overrun by lolling tongues of glacial ice. It is situated close to the transform boundary between the South American Plate and the Scotia Plate, and although there is still debate over which plate can claim the island, its tectonic uniqueness is unquestioned. Essentially dragged southeastward from the Tierra del Fuego region, the island recorded volcanism and rifting as Gondwanaland separated into East and West Gondwana about 185 million years ago. Today, visitors can see exposures of Jurassic-aged oceanic crust overlain by Lower Cretaceous sandstones that contain a variety of volcanic sediments.
As you sail up to South Georgia Island, its outline reminds you of an amoeba, riddled with inlets and bays caused by the downcutting of glaciers that have since retreated up their respective valleys. Our first stop on the island was in such an inlet and provided both historical and geologic context for the remainder of the trip.
We landed at Peggotty Bluff in King Haakon Bay, the landing site of Shackleton and the fearless crew of the James Caird, who in May 1916 accomplished a treacherous 1,500-kilometer crossing of the Southern Ocean in the 7-meter-long lifeboat as they attempted to rescue the remaining crew of the Endurance trapped on Elephant Island. From here, they began their bid — a 51-kilometer hike over the uncharted interior of the rugged, glaciated island to reach a whaling station on the opposite coast. Starving, dehydrated, frostbitten and exhausted from the perilous 17-day ocean voyage, Shackleton and two crew members made the hike in just 36 hours.
Fortunately, we had less pressing issues to worry about and could aimlessly wander the cobbled beach that was guarded by vigilant fur seals. The surrounding hills and steep walls of King Haakon Bay — a textbook fjord — expose both folded and undeformed layers of dark gray sediments that vary from shale to conglomerate and record episodic submarine landslides, called turbidity currents or flows. This was the first of many encounters we had with this formation, and only the beginning of retracing Shackleton’s journey.
From King Haakon Bay we traveled south to Drygalski Fjord to visit one of the most unique outcrops of the trip: the ophiolite sequence of the Larsen Harbour Formation. We anchored at the mouth of the harbor and debarked to smaller, faster zodiac boats, which we took all the way to the head of the harbor. Here, we saw vertical diabase dikes slicing through beautiful pillow lavas — slivers of the former Gondwana.
Eastern South Georgia Island
Next, we dropped anchor in Fortuna Bay, which was originally named after a Norwegian-Argentine whaling ship. We got out and hiked the last 5 kilometers of the Shackleton crew’s exhausting journey — from the shores of the bay, up a steep glacial moraine, over exposures of frost-shattered rocks down Shackleton Valley to the whaling station in Stromness Bay. While standing on the crest of the moraine looking northwest at the steep gullies funneling talus into Fortuna Bay, we found it incomprehensible that anyone could have safely descended, especially after such an arduous journey. Our arrival in Stromness — clad in GORE-TEX®, well-hydrated and well-fed — starkly contrasted with the disheveled and malnourished state of Shackleton’s team.
The following day was spent hiking across the Barff Peninsula from Godthul Bay to Cumberland East Bay, clambering up steep cliffs and down through stunning valleys. We were rewarded with views of the Nordenskjöld glacier to the southwest and giant tabular icebergs, colloquially called tabbies, crowding the bay. We crossed the bay, skirting the tabbies, and took the zodiacs to Grytviken, a historical whaling station that now hosts a museum and gift shop operated by the South Georgia Heritage Trust. On Jan. 5, we raised a toast to Shackleton on the 91st anniversary of his death.
Our last overlap with Shackleton’s journey occurred where his ordeal had started: Point Wild on the north coast of Elephant Island. Although we didn’t land at the point, we had excellent views of Pardo Ridge towering over the tiny spit where 21 members of the expedition scratched out a miserable existence for more than 100 days while they waited to learn if Shackleton and the crew of the James Caird had survived the treacherous crossing to South Georgia Island and raised a call for help. Three rescue missions were launched and were turned back by encroaching ice before a fourth finally reached the survivors in late August 1916.
After a raucous greeting from both Chinstrap and Gentoo penguin colonies, we explored Mid- to Late Cretaceous metamorphism at Cape Lookout and the Alpine-style ultramafic complex exposed in the Gibbs Island shear zone. As we rode back to the ship, cold but sated from a day of chasing whales and fascinating geology, as well as the ghosts of the crew of the Endurance, I was struck by how deftly penguins climb steep, friable slopes that would scare even the most daring geologist.
The Great White Whale, er Continent
With our departure from Elephant Island, my attention shifted away from the Shackleton legacy to the surreal prospect of visiting the Antarctic Peninsula. The ship made slow but steady progress through the mosaic of frost-coated multiyear pack ice that is Antarctic Sound, and anchored in Hope Bay, home to Argentina’s Esperanza Station. As we landed in Hut Cove and took our first steps on the continent, we were greeted by Adélie and Gentoo penguins, giant petrels and kelp gulls and a fantastic view directly into the northeast facing cirque of Mount Flora, made famous especially by the Mount Flora Formation, one of the first significant fossil sites discovered in Antarctica.
Approaching the shore of Hope Bay, we were offered a wonderful view of the Scar Hills and the Depot and Kenney glaciers hugging the western flank of Mount Flora. The narrow beach where we landed was littered with slippery volcanic cobbles and our progress was slowed by an imposing snow shelf mantling the slopes of the Scar Hills. The fossil-rich beds of the Mount Flora Formation — containing diverse Jurassic plant taxa in the Flora Glacier Member — are well-known even to nonpaleontologists and recall a time when the great white continent enjoyed a much warmer climate.
However exciting 150-million-year-old ferns are, they couldn’t compete with the determined march of hundreds of Adélie penguins across the snow shelf. A nonstop parade of black and white bowling pins waddled back and forth from the ocean to the rookery. Their marching band precision and unwavering focus were so mesmerizing that I almost forgot that I was standing on Antarctica.
Our next landing site was one that had long held my interest: the remote and mysterious Deception Island. This volcanic island is often portrayed as inaccessible and shrouded in fog or steam, so it is no surprise that some believe it was Jules Verne’s inspiration for the secret base of the Nautilus in “20,000 Leagues Under the Sea.” Even the names for topographic features beg caution: Neptune’s Bellows (a narrow cleft incised through otherwise impenetrable caldera walls), Fumarole Bay (a small bay that offered protection to a now-buried research station) and Neptune’s Window (a small gap in the caldera walls offering views to the southeast). When we visited, reality belied the foreboding mythos; aside from the whipping wind, we enjoyed clear, sunny skies and didn’t encounter any trident-bearing deities.
We stopped in Pendulum Cove to explore a Chilean research base destroyed by consecutive eruptions in the late 1960s and then moved south to Whalers Bay to visit the remains of British Base B, buried by lahars during the 1969 eruption. The ground in both areas was littered with pyroclastic debris, looking like toys strewn across a 4-year-old’s bedroom floor.
Next we visited Cuverville Island, where we could appreciate the rock-collecting process that Gentoo penguins engage in to create safe and warm roosts for their young. At all times, seemingly, they are either sitting on a nest of pebbles or attempting to filch pebbles from neighbors, making for an oddly choreographed scene of avian robbery.
From Cuverville, we continued south through the Gerlache Strait for a zodiac cruise around, and hike on, Booth Island. This location was by far the most memorable, not because the geology was especially unique but because of the eerie solitude and late evening light. During the zodiac cruise, we passed numerous icebergs and ice floes — one of which carried a languid but intimidating leopard seal. As we skirted the larger icebergs under a setting sun, the water became darker and the ice turned a sapphire blue, backlit by a red and purple sky.
We then enjoyed an evening hike to Charcot Point, which provided the most humbling view of the trip: The bay to the south was choked with grounded icebergs of varying sizes, from small growlers with their ice sail barely poking through the surface to small foundering tabbies backlit by one of the most stunning sunsets of the trip. It was a veritable graveyard of bergs wasting away under relentless wave action and “warm” summer temperatures.
Beholding the sheer size and number of icebergs was quite emotional. Booth Island is a special place — a microcosm of the Antarctic experience, complete with leopard and crabeater seals, the requisite array of penguins and the ubiquitous icebergs.
We returned to Argentina via the Drake Passage, traveling roughly parallel to the Shackleton Fracture Zone and eventually through Beagle Channel, named for Darwin’s ship, which heralded the end of our journey following in the wake of many great explorers.
Although my fascination with cold, remote locales was rooted in the writings of Arctic explorers, this trip provided a taste of similar trials and landscapes through an Antarctic lens, albeit it from the quarters of a safe, warm ship with plenty of citrus to prevent scurvy.
But in the end, this trip really was about celebrating the legacy and history of the field of geology. Those of us on the trek celebrated the many geologists who had explored these remote places before us and celebrated that we, too, were able to take what was truly a once in a lifetime trip.