Directory

Start date:
Mid November
End date:
Late January
Locations:
McMurdo Dry Valleys
Principle Investigator:
Dr Allan Ashworth
Field season overview:
This austral summer, the research team plans to test the hypothesis that all young lake deposits are devoid of vegetation. Researchers will work from small research camps (three tents at each site) at the following regions: 1. Within the Quartermain Mountains: Mullins Valley, Friedman Valley, Beacon Valley, and Beacon Saddle; 2. Within the central Taylor Valley, including Rhone Platform; 3. Within Pearse Valley and adjacent Friis Hills; and 4. Within the western Olympus Range. At each site, researchers anticipate completion of the following tasks: 1a. Mullins and Friedman valleys: Sample sediments on valley walls to determine the possible existence of paleo lakes impounded by Mullins and Friedman glaciers during late Miocene to Pliocene time. 1b. Central Beacon Valley: Collect shallow, near-surface ice, greater than 8 million years old, for analyses of possible fossil content. 1c. Beacon Saddle: Collect and map sediment from ancient moraines, provisionally dated to greater than 14 million years ago, for analyses of possible fossil content. 2. Central Taylor Valley: Collect and map sediment from Miocene age lakes and examine for possible fossil content. 3. Pearse Valley and Friis Hills: Collect and map sediment from late Miocene and Pliocene age lakes and examine for possible fossil content. 4. Olympus Range: Collect and map undated sediment from ancient moraines near Bull Pass and examine for possible fossil content.
Ancient lake sediments deposited on the margins of former outlet and alpine glaciers in the Dry Valleys region are proving to be an invaluable archive for studies of past climatic and ecological changes. Using a numerical chronology based on analyses of interbedded volcanic ashfall, lake sediments greater than 13 million years ago contain fossils of exceptionally well-preserved mosses, diatoms, ostracods, Nothofagus leaves, wood, and insect remains. Lake sediments from less than 13 million years ago appear to lack all such organic matter. Researcher objectives include: 1. Developing a better characterization of the areal distribution of ancient lakes; 2. Securing a more refined lake chronology; 3. Developing a better characterization of the flora and fauna within each lake system; 4. Producing a geochemical signature for tephra within ice-marginal lakes; and 5. Providing a comparison for terrestrial vegetation mapped previously in the central Transantarctic Mountains.