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Stability of landscapes and ice sheets in the McMurdo Dry ValleysAntarctica
A systematic study of exposure ages of soils and surface deposits

 

Who are we?

We are a group of geologists from the University of Washington studying the soils and rocks of the McMurdo Dry Valleys, Antarctica.  This is our second season in Antarctica.  We arrived at the main U.S. base, McMurdo Station, on December 3, 2005 and now we are getting ready to go camping in the Dry Valleys for six weeks to collect rock and soil samples.  We will then go back to Seattle, WA in February, 2006 to analyze the samples. 

You can use the links on the left side of the page to navigate our webpage.  There is a People page where you can learn more about us.

 

What are we doing?

We want to understand the history of the McMurdo Dry Valleys in Antarctica.  The climate in the Dry Valleys is called a polar desert because it is very dry there and it is very cold.  It is believed that the valleys have been very cold and dry for over 10 million years and that the rocks and soil there are not moving at all because it is so cold and dry.  That means that if we could go back in time 10 million years, every rock would be in the exact same place that we find it in today!  We want to learn how the valleys formed, when they formed, and if the rocks reallly aren't moving at all. 

If you want to read the official abstract for the project, click here.

 

Antarctica

Antarctica is the coldest, windiest, highest, and driest continent and it is roughly centered about the south pole.  It has an area of 14 million square kilometers, which is about 1.5 times the size of the entire United States.  98% of Antarctica is covered by a thick, continental ice sheet.  Here is a map of the entire continent of Antarctica.


McMurdo station is located on Ross Island, which is near the "s" in "Ross Sea" in the map above.  Our field area is one of the few ice-free areas of Antarctica, called the McMurdo Dry Valleys.  The McMurdo Dry Valleys are located in the Transantarctic Mountains.  This is a great place for geologists to work because there are so many rocks there.  It is so cold and dry in there that very few things can survive.  Only algae and bacteria grow there, so there are no trees or grasses to cover up the rocks, and there are no animals knocking the rocks over.  The map below shows the Dry Valleys.  The black dots mark the field camp locations from the 2004-05 season.



Abstract:
Stability of landscapes and ice sheets in the McMurdo Dry Valleys, Antarctica
A systematic study of exposure ages of soils and surface deposits

This work will study cosmogenic isotope profiles of rock and sediment in the Dry Valleys of Antarctica to understand their origin. The results will provide important constraints on the history of the East Antarctic Ice Sheet. The near-perfect preservation of volcanic ash and overlying sediments suggests that hyperarid cold conditions have prevailed in the Dry Valleys for over 10 Myr. The survival of these sediments also suggests that warm-based ice has not entered the valley system and ice sheet expansion has been minimal. Other evidence, however, suggests that the Dry Valleys have experienced considerably more sediment erosion than generally believed: 1) the cosmogenic exposure ages of boulders and bedrock in the Valleys all show generally younger ages than volcanic ash deposits used to determine minimum ages of moraines and drifts, 2) there appears to be a discrepancy between the suggested extreme preservation of unconsolidated slope deposits (>10 Myr) and adjacent bedrock that has eroded 2.6-6 m during the same time interval. The fact that the till and moraine exposure ages generally post date the overlying volcanic ash deposits could reflect expansion of continental ice sheet into the Dry Valleys with cold-based ice, thus both preserving the landscape and shielding the surfaces from cosmic radiation. Another plausible explanation of the young cosmogenic exposure ages is erosion of the sediments and gradual exhumation of formerly buried boulders to the surface. Cosmogenic isotope systematics are especially well suited to address these questions. We will measure multiple cosmogenic isotopes in profiles of rock and sediment to determine the minimum exposure ages, the degree of soil stability or mixing, and the shielding history of surfaces by cold based ice. We expect to obtain unambiguous minimum ages for deposits. In addition, we should be able to identify areas disturbed by periglacial activity, constrain the timing of such activity, and account for the patchy preservation of important stratigraphic markers such as volcanic ash. The broader impacts of this project include graduate and undergraduate education, and improving our understanding of the dynamics of Southern Hemisphere climate on timescales of millions of years, which has major implications for understanding the controls and impacts of global climate change.