CHEMICAL VS. PHYSICAL WEATHERING IN STREAMS OF A POLAR DESERT, ANTARCTICA

In a series of papers from 1967 to 1983 Gunter Faure and his students established that chemical weathering did occur in the polar desert streams of the McMurdo Dry Valleys, Antarctica. This provocative and pioneering work has provided the underpinning for more recent research that has examined this phenomenon in more detail. A series of papers published in the past five years confirms the early work of Faure and his colleagues, and establishes the loci and mechanisms of weathering taking place in these environments. The geomorphology of the streams exerts important constraints on the weathering rates as well as the relative amounts of chemical versus physical weathering within individual streams. Here we present data from seven streams in the Taylor Valley (TV) as well as information from the longest river in Antarctica, the Onyx River in Wright Valley. In TV, streams that have low gradients and/or abundant benthic algae populations are dominated by chemical weathering while shorter, steeper and biologically inactive streams have higher physical to chemical weathering ratios. The exception to this is the Onyx River, which appears to be dominated by physical weathering. These data support our earlier conclusions regarding the mechanisms of chemical weathering and help us to develop a conceptual model of weathering in these systems.