The re-advance of the Franz Joseph Glacier that led to the formation of New Zealand’s Waiho Loop moraine during the last glacial termination was driven by a landslide from a nearby mountain, rather than climatic changes. The Waiho Loop, located in the Southern Alps of New Zealand, had been interpreted as evidence for Southern Hemisphere cooling during the Younger Dryas cold reversal.
Online this week in Nature Geoscience, James Shulmeister and colleagues study a large suite of rock samples collected from the Waiho Loop moraine ? the debris material carried and deposited by the glacier. Based on an analysis of the rock types and the grain characteristics of the material, they concluded that the moraine most likely represented the products of a massive landslide, rather than typical glacier transport. They suggest that a landslide from nearby Mount Roon may have blanketed the glacier, protecting it from surface ice loss and ultimately causing the glacial advance.
The authors suggest that landslides may play a bigger role in causing isolated glacial advances than previously thought, and suggest care must be taken when interpreting similar isolated moraines elsewhere.