Stone circles: form and soil kinematics

Abstract

Distinct surface patterns are ubiquitous and diverse in soils of polar and alpine regions, where the ground temperature oscillates about 0°C. They constitute some of the most striking examples of clearly visible, abiotic self-organization in nature. This paper outlines the interplay of frost-related physical processes that produce these patterns spontaneously and presents unique data documenting subsurface soil rotational motion and surface displacement spanning 20 years in well-developed circles of soil outlined by gravel ridges. These sorted circles are particularly attractive research targets for a number of reasons that provide focus for this paper: (i) their exceptional geometric regularity captures the attention of any observer; (ii) they are currently forming and evolving, hence the underlying processes can be monitored readily, especially because they are localized near the ground surface on a scale of metres, which facilitates comprehensive characterization; and (iii) a recent, highly successful numerical model of sorted circle development helps to draw attention to particular field observations that can be used to assess the model, its assumptions and parameter choices, and to the considerable potential for synergetic field and modelling studies.

High-resolution electrical resistivity tomography applied to patterned ground, Wedel Jarlsberg Land, south-west Spitsbergen

“…The evident mimicking the shape of the permafrost table by the geometry of sorted stone circles (or vice versa), as seen in Profile 1, has been noted by several previous authors. However, the relationship was presented in an opposite way, i.e., depressions of the permafrost table were located under the central parts of the structures (e.g., Troll 1958;Hallet & Prestrud 1986;Kling 1997;Hallet 2013). Other authors did not imply such a relationship (Jahn 1975;Tedrow 1977).…”

“…This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Peterson & Krantz 2008); (ii) buoyancy-driven soil circulation (e.g., Ray et al 1983;Hallet & Prestrud 1986;Hallet 1998Hallet , 2013 and (iii) free convection of soil porewater during thaw (e.g., Krantz 1990) are emphasized.…”

The distribution and paleoclimate implications of periglacial landforms in eastern Australia

“…The variance in terminology for the same landform process is unnecessary and in the literature sorted stone polygons and circles (Feuillet et al 2012, Hallet 2013) are the most widely used term for these features.…”

“…These landforms occur where exposed ground surfaces consisting of a range of clasts sizes are affected by significant diurnal freeze-thaw cycles (Washburn 1979, Feuillet et al 2012, Hallet 2013. Patterned ground can be either a) sorted whereby surface sediments are sorted into bimodal accumulations of sediment or b) non-sorted patterned ground where vegetation cover and or soil colour can be important indications of development (Krantz 1990).…”

“…Patterned ground can be either a) sorted whereby surface sediments are sorted into bimodal accumulations of sediment or b) non-sorted patterned ground where vegetation cover and or soil colour can be important indications of development (Krantz 1990). The most widely recognised process of patterned ground formation is by ground ice preferentially sorting clasts on and immediately below the ground surface into circular or striped patterns based on grainsize (Boelhouwers et al 2003, Hallet 2013). This process is promoted by saturated soils susceptible to greater swelling upon freezing (Grab 1997).…”