#7 - Upper Wright Valley

Before I get started, I found a better labeled map that shows all the sites we visited in both our field seasons to give you a better idea of the places we visited. I'll be talking about our trip to a few of the smaller open spots in the northern Convoy Range in my next email, this email will focus on our trip up the Wright Valley where we were dropped on a helicopter day trip in the areas just east of the Labyrinth, around Lake Vanda and Prospect Mesa. Yesterday's email focused on the area between Lake Vida and Victoria Upper glacier, though the other two groups (as we were split into 3 groups of two) moved from Bull Pass to Lake Vida and the lower part of Victoria Valley near the Sand Dune Field. 

I was asked a few questions, though I'll just talk about one of them in this email. Though it doesn't look like it, the Dry Valleys are actually an ecologically active area, when I describe Marshall Valley I'll focus on the living things in these desolate and tough conditions. I was asked about precious minerals as well, and the answer is: there are none. At least no gold. There some strange rocks though, such a Kenyite, a mix of basalt and big anorthosite feldspar crystals that only form in certain divergent tectonic plate boundaries, so two places: Kenya in the Great Rift Valley, and Ross Island, but the Ross Ice sheet actively transported many basalts and kenyites from Ross Island and Brown Peninsula into some of the Dry Valleys, including Taylor, and the Royal Society Valleys, including Salmo, Garwood, Marshall and Miers Valleys.

Upper Wright Valley: Human Expeditions, Katabatic Winds, and Seal Traps

I was asked if there was much human history and impacts that can be seen in the Valleys. Turns out, if you pay attention, you can usually find signs of just about every time someone has ventured into the valleys. Last year we found seal mummies with their heads clearly chopped off with knives by Scott's crew (1910-1912) near Mummy Pond in Taylor Valley, a known site of the first expedition into the valleys. The valleys were essentially un-visited for another 30 years due to lack of funding and the world wars. Later on, as the US Navy and the NSF was scoping a spot for McMurdo Station in the late 1950s, the valleys were revisited and several sites were considered, including Marble Point along the coast (See map, I'll be talking about Marble Point in more detail in a later email). Though McMurdo was eventually placed on Ross Island, relics of old expeditions can be seen. As the Navy was exploring the valleys, they laid down survival caches and "dunny" (New Zealand speak for the bathroom) spots in various places. As we're looking for bones, we'll sometimes find toilet paper that is the roughly the same color from the 1950s until 1978 when the Antarctic Conservation Act designated the Dry Valleys as an Antarctic Specially Managed Area (ASPA). 

 

Left - A view of the Middle of Wright Valley. The Onyx River, the largest river in Antarctica, flows away from Lake Brownworth to Lake Vanda due to tectonic uplift creating a skewed topographical gradient resulting in a reversed flow direction; inland instead of to the ocean. Right - Tracks from a New Zealand tractor driven to Lake Vanda Station along the Onyx from the late 1950s. For a short period Lake Vanda station was staffed year round by New Zealand. Today Vanda Station remains staffed during the summer. Notice that the tracks look brand new despite being over 50 years old. 

Getting back to our research mission, we found that seals are generally distributed fairly evenly throughout the Valleys, except for several specific types of areas: bottlenecks, generally edges of glaciers that they have trouble climbing up and over or cliffs and closed off areas, such as the area directly beneath the Labyrinth. 

 

Left- Cliffs where Wright Valley thins out just below the Labyrinth. We found over 10 seal carcasses and scattered bones in this area. Right - Looking down toward the middle of Wright Valley. Many of the boulders in here would appear to be tough for seals to maneuver, yet they trudged not only through here but a few have sighted up and over the edge into the Labyrinth. 

 

Left - traveling down valley from the cliffs, we found we needed to climb over a Rock Glacier, often found only on Mars. Rock glaciers are a roughly 50-50 mix of rock and ice that flow very slowly and are formed when snow patches and glacial ice becomes buried under sediments. We found several seal carcasses on the rock glacier, many of them fairly early in stage of decomposition. Right - The "naptime while waiting for a helicopter pickup" photo with Lake Vanda in the background and the famous "bunny boots" in the foreground. However, katabatic winds were blowing pretty strongly to the point where we weren't certain of a pickup. Luckily the winds didn't prevent the helicopter from reaching us at the end of the day.

Winds are a major component of the environment in the Dry Valleys. Typically there are two sources of wind, cold constant and moist winds from the coast that blow in from the Ross Sea at around 5-20 knots and warm, dry and strong katabatic winds that blow in from the continent at anywhere from 5-30 knots, with gusts higher than 60 at times. For reference, the "shovel test," in which the winds can keep a shovel from falling over, occurs at around 40 knots. For those in Southern California, you may recognize katabatic winds as the Santa Anas. Katabatic winds are essentially gravity driven currents of strong winds that blow from high areas to low and expand as they descend, becoming drier and even stronger. During the winter katabatic winds here will blow as strongly as 200 mph, which often send seal carcasses flying and generally sandblast mummies. 

We experienced a 3 day katabatic windstorm, which started when we noticed the constant daily coastal wind stopped for about 15 minutes, then the wind direction began to pick up in the opposite direction. Unlike the coastal winds which would typically stop during the the night, the katabatic winds blew throughout the night, reaching a crescendo on the third day when the winds were reaching a constant 20-30 knots. At that point we had to give up on seal sampling, which was getting difficult anyway just because we had to put rocks on our notebooks and sample bags to keep them from blowing away, and go make sure our tents were tied down securely so they wouldn't blow over. Luckily our yellow Scott tents can withstand extreme winds up to 250 mph. 

In a storm on the ice sheet a few years ago, the members of a research team needed to huddle in a single Scott tent since the winds had torn apart and destroyed the other tents. When they left the tent by the time the storm had dissipated, a snowmobile had been blown away. According to Brenda, our 25 season veteran, she had been in a katabatic wind storm where they could hardly breathe inside because the tent was flapping so much. As a result, they couldn't light a match for the stove since the wind was too strong even inside the tent and had to resort to drinking juice packs for three days while huddled in their sleeping bags. Luckily the wind was never that fierce for us. While walking across the rock glacier photographed above, however, we were experiencing coastal winds when out of nowhere a katabatic wind blast nearly knocked us to the ground, and after that strong winds made us worry about our helicopter not being able to get us. Curiously, our other teammates farther down valley on the other side of Lake Vanda were still experiencing coastal winds, which made for some confusion as the helicopter pilots were feeling strong katabatic winds at altitude. 

That's a lot more than I was expecting to talk about winds. I'll try to get some pictures of wind blown seals to show you all in the next email. Still to come: The Convoy Range with Carcass/Bone weathering, Marshall Valley and wildlife in the inland valleys, Cape Roberts and wildlife on the Ross Sea Coast, Glacial reaction to Climate Change in Salmon Valley, Marble Point/Gneiss Point and the Antarctic Conservation Act, all of these with fun seal mummy action, and perhaps a conclusion with the future of the project and some penguins back at McMurdo Station.

As always feel free to ask questions and I'll try to cover them later on.