Deception Island: Pendulum Cove and Whalers Bay

13 January 2013

Deception Island: Pendulum Cove and Whalers Bay

It’s not every day that your ship sails into a volcano before breakfast. The early wake-up call brought us out on deck for the dramatic narrow passage through Neptunes Bellows (no apostrophe, thanks to the early sealers who named the place) into the flooded, collapsed caldera inside Deception Island’s doughnut rim. The towering cliffs we passed between are just a couple ship lengths apart. They show a range of colors, from nearly black to warm brown to yellow ochre to vibrant reds and greens. A beach just inside is decorated with the wreck of a whaling-era supply vessel, a reminder that there is a huge rock in the middle of the channel that our captain carefully avoided.

After breakfast we went ashore at Pendulum Cove, which lies at the far, northern side of the caldera. It was a bumpy quarter mile Zodiac ride in a stiff breeze over one-meter chop to the flat, black sand beach. Empty Zodiacs returning upwind to the ship for more passengers needed a second staff member in the bow for ballast to keep the wind from flipping the boat. This was one of those landings where in the end everyone gets soaked on the ride home, usually to lots of laughs, though the boat drivers who made many trips got pretty chilled.

It was an easy walk to outcrops of coarse volcanic tuff and ash. We also explored the ruins of a former research station overrun by an eruption, and climbed on a small glacier tongue thickly layered with windblown and waterborne layers of frozen black debris. The more ambitious hoofed it up steep ridges for windy views of the whole caldera. Occasional Gentoo and Chinstrap Penguins hopped out onto the beach to rest and the waves washed up beautiful sea urchins and a brittle star.

Ian Dalziel explains the island’s geology: “Deception lies at the southwest end of the Bransfield Strait rift, a back-arc extensional feature southeast of, and parallel to, the extinct South Shetlands arc that we visited on the 11^th [at King George Island]. Deception is a large basalt-andesite shield volcano with a 10 km diameter ‘restless’ caldera and a complex history of pre- and post-caldera eruptions.

“In the morning we anchored in Pendulum Cove and studied the largely phreatomagmatic post-caldera eruptive products of the formation named after the cove. These drape the interior of the caldera and can locally be seen to overlie the deposits of the pre-caldera Fumarole Bay, Basaltic Shield and Outer Coast Tuff formations. These were visited in the afternoon from Whalers Bay and Neptunes Window, a breach in the upper part of the caldera wall near its Neptunes Bellows entrance. They consist respectively of tephra eruptions from multiple centers, Strombolian/Hawaiian activity that constructed a small shield volcano, and a large eruption of tuff. These were very well displayed in the late afternoon sun as we exited Neptunes Bellows, together with a capping of the post-caldera Pendulum Cove Formation.”

During lunch the ship repositioned a few kilometers south to Whalers Bay, just inside the mouth of Neptunes Bellows, where we were offered two adventures: an ambitious hike and/or a ludicrous swim. First stop for almost everyone was Neptunes Window, an easy walk up to a notch in the outer rim of the caldera. Standing at the vertiginous cliff rim in a strong ocean wind made for a giddy bit of geologizing. On the walk to the lookout, we noticed that a large leopard seal hauled out on the beach ignored human passers-by — but not the hungry skua that nipped it on the flipper.

Ted Cheeseman and Tim Carr led a long hike up and over a severely windswept 500m shoulder of the caldera to the huge Chinstrap Penguin colony at Baily Head. This colony has declined more than 50% since the 1988-89 breeding season, probably because of rapid climate change in the Peninsula area, yet still numbers 50,000 pairs. The hike was physically challenging with the soft, steep footing on ash and snow, but the views from the top were spectacular and it was a great reward to run down the same slopes in giant leaps. We estimated the wind on top at a steady 45 knots. That’s enough to lean your body weight on, and to make the lighter of us hold on to someone else.

While hikers were on the ridge, an assembly of the brave readied themselves for a dip in the (somewhat) geothermally heated waters on the beach. About 30 hardy souls in swimsuits and some with hats as well ran into the ice water and tried to find warmth in the sand where the heated water bubbles up. It was a scene of shrieking in the beach mist, followed by confusion and hopping on the hot sand as people tried to figure out how to get warm/dry/covered without getting pernicious black sand into every fold of fabric. Staff handed out clean towels and ran ferries back to the ship where both roof hot tub (104˚ F) and Russian sauna (80˚ C!) awaited. The sight of people in full Antarctic garb next to bathers in swim suits brought home just how much chutzpah it takes to jump in here.

Sailing out through Neptunes Bellows we were greeted by gorgeous icebergs, sunshine, puffy clouds, and also large swells growing to 4-5 meters. The ship listed and rolled for some time with the seas and wind on our starboard until we cleared the island and turned to face into the swell. Several whales were spotted but the whitecaps and fantastic spray over the bow probably obscured more. It was an interesting supper with ship’s movement. Amazingly, at dessert we were taught a brand new song by passenger and ship’s bard Helen Nattrass, immortalizing in verse our “screams and splashes” — and the “naughty people clicking” photos of it all.

Quote of the day from Cheesemans’ staff naturalist Jim Danzenbaker, while holding boats at the Pendulum Cove beach: “I’m in a volcano in Antarctica and I’m still cold!”

– Kate Spencer, Staff Naturalist; Cheesemans’ Ecology Safaris