Allow me to share some recent happenings from the last two days. On Friday morning our helicopter pilot, Flo, picked us up to be flown into Wright Valley to set up some gaging stations. Wright Valley is the first valley north of Taylor Valley, and to get there we took a highly scenic helo trip through the Asgard Range.
View from above the Asgard Range
In the photo shown above, notice polygon patterned ground . This is an interesting landscape feature of cold regions. Patterned ground forms as a result of sequential freezing and thawing of the subsurface, and can be found in most any region underlain by continuous or discontinuous permafrost. Permafrost is defined as soil which has been frozen for more than 2 years. Permafrost is found several meters beneath the ground surface. The shallow sub-surface, which is thawed and then re-frozen each year is called the “active layer”. As the active layer freezes it often cracks, which makes sense because water expands when it freezes. Dont believe me? Fill up a water bottle all the way to the top and stick it in the freezer for a while – see what happens to the bottle. Anyways, the cracked active-layer gets filled with water, snow, and sand. When the winter months come along, this new moisture and sediment re-freezes and expands the cracks further. This is essentially “ice-wedging” – the dominant process behind patterned ground.
We flew into the Wright Valley to set up a gage at the Onyx River. Although currently not flowing, the Onyx river is the largest river in the McMurdo Dry Valleys. In the photo below you can make out the fluvial channel structure, which has been imprinted on the landscape by the movement of water through the valley bottom.
The Onyx river, although it dosen’t have any water yet, you can make out the braided channel structure. Look closely.
At each gage we survey the relative elevation of important features, necessary for the conversion of water height to discharge. Basically the gage boxes record the height of water, also known as stage, at any given moment. When water is flowing we make manual measurements of discharge (volume of water passing per unit of time). By mathematically relating continuous stage measurements to occasional discharge measurements, we can estimate the continuous discharge record of the stream. This is also known as a “rating.” The surveying allows us to account for changes in the infrastructure of the gage system, which is highly important to work the “rating.”
Doing my part to help survey at the Onyx River.
After we wrapped-up surveying, we climbed back in the helo to go scope out a candidate position for a radio antenna. Some of the sites we monitor are rigged up to send data back to the U.S., near real-time. This process is made possible by transmitting a signal from the gage box to a radio antenna, which can relay the signal to McMurdo Station. This complicated process requires that antennae be within eye-shot of the gage boxes, which is why we choose to position antennae at higher elevations. Thank goodness for helicopters.
Checking out the peaks around Wright Valley. McMurdo Sound in the distance
Although climbing above Antarctic mountain ranges in a helicopter is an awesome experience. It is also extremely nauseating, at least I thought so! I spent the remainder of the helicopter ride with a bag in my hands anticipating vomit. Thankfully, I held my own.
We needed to abort our scheduled mission due to the gnarly inbound weather. We were dropped off at Lake Bonney Camp. Lake Bonney is located at the far western edge of Taylor Valley and it backs up against the Taylor Glacier. The lake is split into two lobes – West Bonney and East Bonney. Similar to Lake Fryxell, many glacier-fed steams drain into the lake.
From right to left: Talor Glacier, Lake Bonney West Lobe, and Lake Bonney East Lobe.
There several streams draining the Taylor glacier and feeding into Lake Bonney: Lawson, Sante Fe, Sharpe, and Lyons. These streams give us a reason to visit one of the most novel and interesting areas of Taylor Valley: Blood Falls. Notice the rust colored patch on Lake Bonney West Lobe, above? This is a result of Blood Falls. I cant speak to eloquently about this site, as I am certainly not an expert – but I’ll do the best I can. This part of the Taylor Glacier seeps very very salty and iron-rich water, several times the salinity of sea water. It is believed that relict sea water is trapped within the Taylor Glacier. As this hypersaline and iron-rich water seeps out, iron ions are oxidized as they come in contact with atmospheric oxygen, resulting the highly identifiable orange color. Also, turns out, this water sustains life! Many different kinds or micro-organisms are able to use sulfate as a catalyst to respire with iron ions and metabolize organic matter in the water, all in an anoxic (no oxygen) environment. Jill Mikucki is a microbiologist who has done a ton of fantastic science on this site. This is one aspect of the Dry Valleys, which can be potentially analogous to life on Mars.
Blood Falls hypersaline discharge
Tyler stands amazed by blood falls.
Currently, I am situated at Lake Bonney Camp for the weekend. Bonney Camp is a medium sized camp, maybe twice the size of F6 Camp. I look forward to hanging out with a whole bunch of limnologists (lake scientists) tonight. Should be a fantastic time.