Polygonal ground in the McMurdo Dry Valleys of Antarctica and its relationship to ice-table depth and the recent Antarctic climate history

• Published in: Antarctic Science
• Main Authors: Mellon, Michael T., Mckay, Christopher P., Heldmann, Jennifer L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2013
• Subjects: Geology; Ecology, Evolution, Behavior and Systematics; Oceanography; Antarctic; The Antarctic; McMurdo Dry Valleys; Beacon Valley; Beacon Heights; Antarc*; Antarctic Science; Antarctica; Ice; permafrost
• Online Access: http://dx.doi.org/10.1017/s0954102013000710; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102013000710

Abstract The occurrence of dry permafrost overlying ice-rich permafrost is unique to the Antarctic Dry Valleys on Earth and to the high latitudes of Mars. The stability and distribution of this ice are poorly understood and fundamental to understanding the Antarctic climate as far back as a few million years. Polygonal patterned ground is nearly ubiquitous in these regions and is integrally linked to the history of the icy permafrost and climate. We examined the morphology of polygonal ground in Beacon Valley and the Beacon Heights region of the Antarctic Dry Valleys, and show that polygon size is correlated with ice-table depth (the boundary between dry and ice-rich permafrost). A numerical model of seasonal stress in permafrost shows that the ice-table depth is a dominant factor. Remote sensing and field observations of polygon size are therefore important tools for investigating subsurface ice. Polygons are long-lived landforms and observed characteristics indicate no major fluctuations in the ice-table depth during their development. We conclude that the Beacon Valley and Beacon Heights polygons have developed for at least 10 4 years to achieve their present mature-stage morphology and that the ice-table depth has been stable for a similar length of time.