A River Runs Through It

    We recently came back from sampling in Wright Valley which is parallel to Taylor Valley. Wright Valley is a little dryer with fewer glaciers. It does have a glacier blocking the ocean side - causing the meltwater stream to flow away from McMurdo Sound. The result is Antarctica's longest river.

    Bill Henske along the Onyx River in Wright Valley, Antarctica
    Bill Henske along the Onyx River in Wright Valley, Antarctica.

    As the longest river, it's not very long. About 20 miles long and it flows into beautiful Lake Vanda. The lakes in the Dry Valleys don't have outlets so the journey of the river ends there, with water evaporating or sublimating as fast as it collects. In some years the flow is so low that the river doesn't make it to Lake Vanda.

    We came here to support some research on the Eudorylaimus nematode habitats and distribution work. While there, Dr. Jeb Barrett described this type of community called a hypolith. Hypoliths are organisms that live on rocks - either underground or inside cracks and crevices. If you read my post about endoliths - they are like that but outside. They take this lifestyle for all the same reasons - protection from low temperatures and drying, access to nutrients and moisture, and protection from UV radiation. Jeb gave Ariel and me a tutorial on how to find these creatures.

    Searching for hypoliths
    Searching for hypoliths.

    The hypoliths prefer quartz rocks not much bigger than a golf ball. They need the rock to be embedded in the substrate and the soil needs to have some moisture but not be wet. Onyx river was a great place to find these. The conditions along the river and the available rock types meant that it was pretty easy to find them. We collected a few small samples and put the rest back to continue growing. As with most organisms in Antarctica, growth is very slow so minimizing our impact is essential.

    Sample of a hypolith
    Sample of a hypolith.

    Oh - I found this weird rock. A cool thing about Antarctic rocks is that they weather but often don't erode (I hope my students get the distinction). You often find rocks weathered apart but all the parts are still sitting there, together. This weird rock and how it came to be is the story of the polygons. All over the Dry Valleys there are these structures called polygons covering the valley floors. Polygons are the shape that results when frozen ground with dry soil is pushed up from the freeze that cycle. These shapes are about 20-40 meters wide and might remind you of a beehive pattern. I have seen several times now where there is a boulder in the path of a polygon crack and it is cracked in half. This is the biggest I've seen. I would love be there when this happens. I wonder if it is fast or slow?

    The power of permafrost
    The power of permafrost.

    View of polygons in soil
    View of polygons in soil at Beacon Valley.

    Make sure to watch my video about hypoliths and the Onyx River!

    Gearing up for Resupply

    Recently the McMurdo contractors began getting the ice pier ready for the supply ships to come in. The ice pier is a giant, thick piece of ice covered in rocks. It allows big ships to tie off to it so they can load and offload cargo without a large port. In the picture you can se the first vessel of the season, the Ocean Giant, from the trail above Hut Point.

    Here is a cool link if you want to keep track of McMurdo and its activities McMurdo Ice Pier Webcam.

    Ocean Giant with next year's supplies
    Ocean Giant with next year's supplies.

    McMurdo Station, Antarctica
    Weather Summary
    Cloudy, light snow
    Wind Speed
    SE @ 17 gusting 27 (more if you ask me)
    Wind Chill


    Sterling Diether

    What is the largest polygon field in Antarctica? What factors contribute to how big a polygon field will be? Thanks. I am from Kevin Dickerson's class.

    Bill Henske

    Hi Sterling- that's a good question. I'm not really sure. The largest I saw was going into Beacon Valley. They are large enough to be seen on Google Earth- at least when the image is from the summer and there is a little snow in the polygon cracks. If you go to Google Earth and go through Miers Valley or Beacon Valley you can see the polygon shapes. I would guess it's the size of the valley and the presence of soil/loose rock that determines what is polygon'd. You won't see them on steep slopes either.

    Taylor Jensen

    Why is it so important for you to take samples of Hypoliths? What kind of tests do you run on these samples?
    Thanks! I am from Mr. Dickerson's class.

    Bill Henske

    Thats a really good question! We don't want to just collect things to be collecting them. We are very conscientious when removing specimens- even rocks- from the Dry Valleys.
    One of our team members, Ariel Waldman, is doing a documentary on the scale of the Dry Valleys from the smallest to the largest. Taking a few samples to the lab allows us to document them in the best condition- temperature, lighting, etc. so that the images and footage are the best possible quality and the best representation of what they look like and how they work. It's much harder to do this in 40 mph winds with -0F windchill! The can also be used later to run DNA analysis to determine the species/taxa that make up the hypolith.

    Lukaah Marlowe

    Hello! I've got two questions:

    How do the water levels of the Onyx River vary throughout the year?

    How has climate change impacted the Onyx River over the last few decades?

    Bill Henske

    Hi Lukaah- There is a lot of data on the changes in glacial melt over time. At first it didn't really seem to be related to other variables. It did fluctuate significantly- some year the water would dry up or soak in before getting to lake Vanda, other years there was so much melt that a team (not a US team) rafted it. Recently the melt has been correlated to the fluctuation of the ozone hole- in years of larger holes or when it is more directly over the Dry Valleys, there is much greater melt. The ozone hole has probably always existed but was drastically increased from chemicals humans released into the atmosphere that broke down ozone molecules. The ozone layer typically reflects uv light back into space but when it passes through the hole its energy can result in increased melt. So- climate change but not the same as we normally talk about- greenhouse gas based

    Liam Missey

    Hi Mr Henske. I was wondering how the river isn't frozen yet because in antarctica its cold.

    Bill Henske

    Hi Liam- Good question. You are right- It has only barely gotten above freezing and not for very long. Even though the air is always below freezing, the ground isn't. Because the soil is dense and absorbs light (turning it into thermal energy) it is warmer. The light in the Antarctic summer is also 24 hours a day and from 360 degrees through out the day- so lots of light energy.
    Also- much of the water is also high in dissolved minerals. This lowers the freezing point of water. That's why putting salt on ice melts it. It isn't warmer, it just a lower freezing point.

    Max Brown

    how is the river not frozen?

    Bill Henske

    Hi Max- Liam had the same question above but there is more to it - since the water is moving once it thaws, it has more kinetic energy which prevents it from forming ice. In places along the Onyx where the current slows down, it does refreeze.

    Catherine Rohlfing

    Hi Mr Henke. Does the temperature affect the type of samples you collect?

    Bill Henske

    Hi Catherine! The air temperature doesn't matter that much because we are collecting the animals that live in the soil, lake, rocks, etc. That's the reason they live there- better conditions for life. If the soil is frozen it may be very hard to find any animals even though they are still there. The go into a state called anhydrobiosis- they remove the water from all there cells, becoming dormant until conditions improve. This prevents them from dying but they can no longer do any "living stuff" like eating, squirming, mating, etc. They can stay like this for a long time- until the next year or maybe 1000s years. No one really knows the limit. They won't really look like an animal when they are in this state so they are hard to count. Moisture levels have a much bigger effect on the types of organisms in our samples.

    william ode

    hello, Mr. henske I was wondering if it was cold enough for the lake to freeze would that affect the samples you take or if that is irreleveant

    Bill Henske

    Hi William- One of the weird things is that some lakes do not freeze all the way (some do). The mass of the ice on top increases the pressure and thus the temperature of the molecules in the lake- keeping them a liquid. It's not exactly water though. There are large concentrations of minerals dissolved in the lake water, especially at lower depths. All of the animals have ways of surviving to the next generation being totally frozen. When scientists look at whats in the lake they often sample the sediment as well because that is where many will spend their dormant time.

    Meg Flynn

    Hi Mr. Henske, I was wondering how the river still isn't frozen since it's so cold there.

    Julien Pierce

    Hey Henske! Have you figured out if Antarctica rocks weather slowly or fast?
    Also with it being cold wouldn't it weather slowly since it can't really erode?

    Oh also can water get trapped in the rocks? If they can have you found any?

    Bill Henske

    Julien- you should be down here doing geology! You are right- without water, weathering is much slower. Erosion happens but mostly just due to stuff falling off mountains when the rocks crack. If you saw my post about the polygons, there are huge upheavals of the entire valley floors where rocks are cracked and smashed as the soil expands and contracts with freezing. That probably causes some of the weathering. Along the meltwater streams there is water in the soil that gets absorbed into rocks. Some places water flows into the soil and then continues to travel through the soil as it slowly evaporates. When that happens it leaves behind all of the chemicals it has eroded.

    Bill Henske

    Hi Meg- When water is moving it has additional kinetic energy. Once the water slows down it will freeze one it hits the right temperature. The water isn't pure water though- it is full of salts and chemicals weathered and eroded from the rocks and soil. With these things dissolved in the water, it lowers its freezing point. Like when you put salt on an icy sidewalk and it melts the ice. It doesn't make it warmer- just changes the temperature where it is a solid.

    Logan Krekeler

    Hey Henske! I was wondering why there was not very much snow. I'd assume it is below freezing temperature, so is the sun melting the snow, or is the climate preventing snow from falling?

    Bill Henske

    Hi Logan- It can't snow if there is no water in the air. When it does snow sometimes, it blows away or sublimates very quickly in the dry air. The climate of Antarctica is separated from the rest of the southern hemisphere by the circumpolar current. This keeps the warm water/air to the north and the cold air to the south. The warmer water puts lots of water into the air but it doesnt travel south. Like the northern hemisphere most weather travels from west to east. The positive thing about this is that it keeps Antarctica frozen even as we change the climate in other places. Unfortunately we are seeing some signs of climate change here still.

    Henry Shaw

    Hi! I am from Busby's class! My questions are a. now that you have visited the hardest continent to visit, will you try and visit every continent? My other question is, Do you guys try to keep the area clean? Is there trash everywhere like Mount Everest? If it is clean, is all of Antarctica clean from human trash? Thanks!

    Bill Henske

    Hi Henry- I love your question. I would like to visit all of the continents. I only have Africa left now because on the flight down I had a layover on New Zealand which is considered part of the Australian continent (although recently some have determined it is its own continent)
    On Antarctica I found 2 pieces of trash in 6 weeks and one was over 60 years old. Basically you will not see any signs of humans outside of McMurdo. I think if someone saw you litter on purpose you would be sent home. We went to the craft room to make a trophy for someone and they said glitter is actually illegal on the continent. Most things are not painted anymore because the paint chips off and enters the environment. You are not even supposed to leave footprints if possible. Everyone leaving town has to carry a pee bottle to bring their pee home. If something blows away you have to file a report about it. If a snowmobile drips oil you have to dig out all the ice it soaked into. Everyone is very serious about keeping it pristine.


    Why is the longest river so short?/ Why isn't there a larger one?

    Bill Henske

    Hi Jasper- The average temperature is well below the freezing point of water and most of the continent is covered in a 1-2 mile thick sheet of ice. There just arent a lot of places where you find liquid water!