Antarctica Blood Falls' Red Water Explained
There are many striking, even head-spinning sights in Antarctica: from fantastically shaped icebergs and towering ice cliffs to 10,000-foot-plus black peaks rising out of frozen nothingness. Few are quite so arresting, however, as Blood Falls, perhaps the White Continent’s most mysterious-looking—certainly its most gory-looking—natural landmarks.
In this article, we’ll explore this supernatural-seeming feature of the Antarctic landscape, about which recent research has shed lots of fascinating light.
Blood Falls lies at the terminus of the Taylor Glacier, located in the Taylor Valley of Victoria Land. The Taylor Valley is the southernmost of the main McMurdo Dry Valleys, mostly bare glens within the Transantarctic Mountains that collectively encompass the largest swath of ice-free ground—in other words, the largest so-called oasis—in Antarctica.
The McMurdo Dry Valleys lie near the borderland of the two great continental ice sheets of the White Continent: the West Antarctic Ice Sheet and East Antarctic Ice Sheet, both of which have made incursions into these oases in the prehistoric past. The Taylor Glacier is an eastern arm of the East Antarctic Ice Sheet.
At the snout of the Taylor Glacier lies the frozen-over Lake Bonney, a proglacial lake (that is, one lying at the terminus of a glacier) which is divided into western and eastern sectors. Blood Falls overlooks West Lake Bonney.
So, what exactly is Blood Falls? It’s an outflow of brine—in other words, hypersaline water—sloshing out from the northern edge of the Taylor Glacier’s terminus. It gets its name from its shocking red color, which stains the ice and the morainal soil edging West Lake Bonney to form a rather grisly crimson fan.
An Australian geologist-explorer, Griffith Tayor, is credited with the first observation of Blood Falls, obtained in 1911 on a foray through the McMurdo Dry Valleys that Taylor led as the senior geologist on Robert Falcon Scott’s British Antarctic (aka Terra Nova) Expedition.(You may have already gathered that Taylor is the namesake of Blood Falls’ glacier and the encircling valley.)
There’s much that scientists are still learning about Blood Falls, but research over the past couple of decades has helped sketch out some of the basic phenomena involved in producing this shocking spew of blood-red brine.
The brine is thought to derive from a reservoir of salty groundwater buried under the ice of the Taylor Glacier. A 2019 study published in the The Journal of Geophysical Research: Biogeosciences suggested the likely origin of this brine is long-ago seawater: The Taylor Valley as well as the Wright Valley to the north are thought to have been periodically flooded by the ocean—they lie along the coast of the Ross Sea’s McMurdo Sound—during periods of higher sea level. This would have turned them into fjords, which, as sea levels subsequently dropped, would have become inland seas.
These inland seas may have then mostly or entirely dried up in the harsh Antarctic climate, leaving behind salt deposits (evaporites) and perhaps residual, highly concentrated salty water.
Later, the encroaching Taylor Glacier is thought to have overridden these saline deposits, which by then may have gone into solution as brine due to meltwater off the snout of the advancing ice.
The high concentration of salt gives the sub-ice water under the Taylor Glacier a lower freezing point. And as it does freeze, latent heat is released that melts edging subglacial ice. These factors seem to explain why the Taylor Glacier’s buried brine forms a network of subglacial rivers and ponds. The channels of this subglacial flow, plus various mechanisms of pressurization and depressurization as well as the movement of the glacial ice itself, are thought to help convey the brine downstream to the terminus of the glacier.
The arrangement of cold ice and the glacier’s edging, ice-cored moraines, 2017 research suggested, help explain why brine mainly issues from the glacier only from particular outflows, which include, in more southerly parts of the glacial terminus, releases directly into Lake Bonney.
Meanwhile, in the northern part of the glacier’s snout, subglacial channels seem to direct brine into an under-ice pool that then discharges onto the surface of the glacier via Blood Falls.
Well, OK, that seems to explain why the water issuing from the Taylor Glacier is so salty, and why it flows underneath the ice rather than fully freezing. But you’re surely still interested in the “blood” part of Blood Falls: What explains a red waterfall in Antarctica?
Back in the day, Griffith and other early scientists speculated that algae in the water produced the garish hue of Blood Falls. There is indeed a rich microbial community in this water, we now know, but today’s geoscientists don’t think that’s where the red color comes from. (Algae, however, does produce some vividly colored snow elsewhere in Antarctica: Read more here!)
Instead, it’s a function of the dissolved iron present in the subglacial brine feeding the falls. That iron undergoes oxidation when the brine, pouring out at Blood Falls, is exposed to oxygen in the air, turning the water red.
A study released in 2023 found that, specifically, oxidation of the water in Blood Falls produces tiny nanospheres of material rich in iron as well as other elements such as calcium and magnesium, which may also contribute to the unique color.
Should you ever work in Antarctica, the falls can be viewed by helicopter from nearby Antarctic research stations such as McMurdo Station (U.S.) or Scott Base (New Zealand), but for everyone else, Blood Falls sadly lies well off the main tourist circuit in Antarctica, far from the Antarctic Peninsula the majority of cruises steer to.
That said, certain cruise packages to the Ross Sea may offer the option of helicopter flights over the McMurdo Dry Valleys, providing a rare opportunity to glimpse this one-of-a-kind glacial waterfall for yourself!
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