Aspect‐controlled weathering observed on a blockfield in dronning maud land, antarctica

Abstract

Investigations of openwork block deposits have the potential to improve understanding of the production of substrates for biological colonisation, the control of geological structure and the impacts of climate change on landforms. As part of research into the morphology and characterisation of a blockfield located on the Northern Buttress of the Vesleskarvet Nunataks, Western Dronning Maud Land, Antarctica (2°W, 71°S), this paper investigates the influence that aspect has on weathering for a blockfield using data collected during the 2009–2012 Austral summer seasons. Proxy data recorded for weathering included rock hardness rebound values as well as visual evidence of flaking, pitting, surface roughness and lichen presence. Aspect was found to affect weathering of blockfield samples across the study site, with the south‐facing sides being the least weathered of the directional aspects. This paper argues that a higher radiation budget associated with slope aspect and angle could drive thermal regimes and subsequent weathering of clast faces. Furthermore, in the absence of abundant precipitation, ice and snow cover become the primary source of moisture in this high‐latitude Antarctic environment.

Integrating structure‐from‐motion photogrammetry into rock weathering field methodologies

“…As noted by Hansen et al () repeated rebound tests at the same location on the rock surface result in artificial increase in rebound strength due to compaction of the surface by the rebound device. To minimize this effect and to avoid artificial compaction of the surface, 10 measurements were taken within a 10 cm × 10 cm space, but never on the exact same position, after manually cleaning the surface of debris such as mud and grit, deposited by wind and surface runoff.…”

Low impact surface hardness testing (Equotip) on porous surfaces – advances in methodology with implications for rock weathering and stone deterioration research

“…As well as being more variable than data from the Schmidt Hammer (Viles et al , ), it is likely that Equotip data obtained from porous and/or weathered rock and stone surfaces will be non‐normally (asymmetrically) distributed. Accordingly Hansen et al () and Alberti et al () find that Equotip data derived from on‐site measurements on weathered stone are affected. Nevertheless, standard parametric statistical methods were employed [e.g.…”

“…gypsum, tuff, limestone, granite) at different stages of weathering, as well as detecting subtle changes in surface hardness (e.g. Hack et al, 1993;Verwaal and Mulder, 1993;Aoki and Matsukura, 2007;Viles et al, 2011;Alberti et al, 2013;Coombes et al, 2013;Hansen et al, 2013). Low rebound values indicate soft, porous and/or weathered stone surfaces, higher values less weathered or case hardened surfaces.…”

Wind as a cooling agent: substrate temperatures are responsible for variable lithobiont‐induced weathering patterns on west‐ and east‐facing limestone bedrock of the Negev

“…Reports regarding the relative xerosis of EF and WF slopes are often contradictory. Whereas some report that EF slopes are warmer (Hall, ) and more xeric than WF slopes (Williams and Robinson, ; Hansen et al , ; Viles and Goudie, ), most researchers maintain that WF slopes are warmer (Thorn, ; Williams and Robinson, ; Desta et al , ; Hall et al , ) and consequently more xeric (Burnett et al , ). Likewise, no agreement exists as to the extent of weathering.…”