#6 - Victoria Valley

Welcome to another exciting edition of my newsletter!

Victoria Valley: Day Trips, Geologizing, and a Dry Dry Valley 

I mentioned in a previous email that we took many helicopter day trips. In fact, over half of our time in the field involved getting on and off helicopters. Normally we requested to take 212s, which are larger, more powerful and could carry our entire group of six, plus a helotech and pilot. The helotech (helicopter technician) makes things a bit easier for us as they help load and unload our gear, including survival bags (anywhere you go outside of McMurdo you are required to have survival bags which have a tent and other supplies to last you 2-3 days in case a helo can't pick you up later in the day) and backpacks full of lunch and seal sampling kits. However, the smaller A-stars can only fit 4 people plus the pilot with no helotech, so you end up having to load an unload your own gear.

While we preferred the 212s (of which there are two, 36 Julie and 08 Hotel) over A-stars (three of these, 31 Lima being the one we flew on, but also 36 Hotel and a Kiwi A-star were around), everyone is subject to the helo schedule, which is usually very busy and so on a couple of day trips we had to take an A-star. The helos run nonstop throughout the day and into the night dropping off supplies, so we were often placed on night helicopter pick ups, which meant a lot of time outside and late dinners when we made it back to camp at the end of the day. Luckily the sun never sets, so that was never a huge problem. Just exhausting.

 

Left- The A-star 31 Lima taking off from Wright Valley camp, a smaller helicopter that took us and dropped our teams of two in Victoria Valley. Right - Flying in 31 Lima over Lake Vida, Victoria Valley

Victoria Valley is roughly in the center of of the Dry Valleys region, just north of Wright Valley and separated from Wright by the Olympus Mountains, and is one of the few areas that has almost never been glaciated as the East Antarctic ice sheet never really made it in that far. Like Wright Valley, it is also blocked from the coast by the Wilson Piedmont, but a small group of mountains prevent the piedmont from spilling into Victoria. Of the valleys that I've been to, this one more so than others really felt like a desert, as there is only one glacial melt stream coming from the Upper Victoria glacier, and it was mostly dried up.

Despite this, seals made it into Victoria Valley and beyond. We ventured into Victoria based on an old map from an early survey of the seals in the 1970s and old field notes with general known locations of mummies. Victoria Valley proved to be difficult in this venture, we couldn't find some of the described seals, but we did find other seal carcasses that weren't mentioned, or seal bones in the stream beds. Despite the low number of samples we found there, it did end up being worth it since these seals and bones were in the later stages of decomposition and could be potentially older. Based on last years results, it appears that whole, mostly intact mummies are on the order of hundreds of years old, while isolated scraps and fragments are in 1000-3000 year old range. Since there is a bias toward more recent individuals being sampled (big intact mummies are easier to find than fragments and aren't easily buried/destroyed) we put an emphasis on collecting weathered, old looking bones. 

 

Left- a view of Lower Victoria Valley above the Olympus Mountains, which divide Wright Valley and Victoria. Right - A view of the Olympus Mountains and Lake Vida. On the side of the Olympus Mountains you can see alternating light and dark rocks. The dark rocks are dolerite sills, an igneous rock similar to basalt that filled in space between the lighter granite. Throughout the Dry Valleys dolerite sills and dikes (horizontal and vertical cracks and fractures that have been filled by magma) are visible in the bedrock on a massive scale.  

 

Left - Looking north at Upper Victoria Glacier with Miocene aged river delta crossed by a large frost crack in the foreground. Frost cracks are formed by the freezing and thawing of soils and extend several meters deep. They occur all over the Dry Valleys and Mars. Right - Looking west at Mt. Insel, mid valley. In the foreground you can see a boulder that has been peeling apart for at least hundreds of thousands of years. Car sized boulders will fall apart in place over time and remain there for several hundred thousand years or longer until they are destroyed by heat expansion and contraction and wind abrasion.

 

Left- A particularly sad looking seal, heavily wind abraded on a river terrace. Right- Looking southeast on old Miocene river delta deposits.

That about does it for this email newsletter. As always, feel free to ask questions if you'd like to know some more details or more specific things. Topics I'll be talking about in later emails: Carcass/bone weathering stages, general camp life, microbial and coastal wildlife.