Australia: The Land Where Time Began

A biography of the Australian continent 

Antarctica - Polygonal Ground in the McMurdo Dry Valleys, it’s Relationship to Depth of the Ice Table and Recent Climatic History

In the Antarctic Dry Valleys dry permafrost has been found that overlies ice-rich permafrost, which is a situation unique to Antarctic Dry Valleys of Earth and the high latitudes on Mars. It is not well understood how stable this ice is and its distribution and these are  fundamental to an understanding of the climate of the Antarctic going back as much as a few million years. Mellon et al. say polygonal patterned ground is almost ubiquitous to these regions and is linked integrally to the climate and the icy permafrost. In Beacon Valley and the Beacon Heights region of the Antarctic Dry Valleys the morphology of polygonal ground was examined by Mellon et al. and they found that the size of the polygons is correlated to the depth of the ice table, which is the boundary between dry permafrost and icy-permafrost. It is shown by a numerical model of seasonal stress in permafrost the depth of the ice table is a dominant factor. Mellon et al. suggest that remote sensing and field observations are therefore important in the investigation of subsurface ice. Polygons are long-lived land forms with observed characteristics that indicate there were no major fluctuations on the depth of the ice table during their development. The conclusion of Mellon et al. is that the polygons of Beacon Valley and Beacon Heights have been developed for at least 10,000 years to develop their mature-stage morphology by the present, and that the depth of the ice table has been stable for a similar length of time.

Sources & Further reading

1. Mellon, M. T., C. P. Mckay and J. L. Heldmann (2013). "Polygonal ground in the McMurdo Dry Valleys of Antarctica and its relationship to ice-table depth and the recent Antarctic climate history." Antarctic Science FirstView: 1-14.