David W. Hedding

Thermal Attributes of Rock Weathering: Zonal or Azonal? A Comparison of Rock Temperatures in Different Environments

Recent investigations into mechanical weathering in cold environments have highlighted products similarities to those of hot deserts. Although general temperature conditions between these two settings are obviously different on the basis of absolute air temperatures, the zonality with respect to thermal changes affecting the rock is less apparent. Data are presented here from four diverse environmental settings with particular emphasis on the fluctuating temperature regime as applicable to rock thermal stress fatigue and thermal shock. The data focus on diurnal oscillations and short-duration rapid changes on rock surfaces at sites in the Antarctic, sub-Antarctic, and at two southern African sites. Comparisons show that different climatic regimes may not be distinctive with respect to rock thermal changes. The azonality is strongly apparent when contrasting the two African sites, a hot desert and cooler alpine setting, in terms of diurnal fluctuations where very similar values are recorded. Overall temperature ranges measured at the Antarctic site approach the magnitude of those in southern Africa, and all sites show a high potential for thermal shock under rapid temperature changes. These findings highlight potential azonality with respect to thermally induced rock weathering and shift the emphasis in cross-climate comparisons to detailed considerations of the moisture regime.

Pronival rampart and protalus rampart: a review of terminology

In the late 1980s, a series of letters in this journal (e.g. Butler, 1986, 1987; Ballantyne, 1987; Porter, 1987; Unwin, 1988; Wilson, 1988) described the history of the early work on ‘pro-talus ramparts’. These letters also highlighted that many different terms, such as winter-talus ridge (Daly, 1912), nivation ridge (Behre, 1933) and protalus rampart (Bryan, 1934), have been used to denote these discrete debris accumulations found at the foot of firn fields. The most common of these terms was ‘protalus rampart’ and it became entrenched in the literature (Ballantyne, 1987) until it evolved yet again when Shakesby and others (1995) proposed replacing the descriptor ‘protalus’ with ‘pronival’ since they concluded that the latter provided a universally appropriate term to describe firn-foot debris accumulations; regardless of their position on the slope. The descriptor ‘pronival’ has largely gained acceptance in the literature (e.g. Hedding, 2008), while some studies (e.g. Hedding and others, 2010) use ‘pronival (protalus)’ so as to avoid any ambiguity. Several recent studies (e.g. Lewis, 2011) continue to use the descriptor ‘protalus’ since interchanging the descriptor ‘protalus’ with ‘pronival’ has not been very problematic in the literature thus far. Scapozza and others (2011) have, however, recently proposed that the term ‘protalus rampart’ be used to define small permafrost creep phenomena (embryonic rock glaciers) in contrast to the former usage of the term to describe pronival ramparts. This may lead to some confusion in the literature because the differentiation of embryonic rock glaciers from pronival ramparts may prove difficult, particularly in relict features, since these features are morphologically similar. To further compound the difficulty in differentiating these features, many of the existing ‘diagnostic criteria’ used to identify pronival ramparts are plagued by circular arguments and assumptions about typical form, constituent material and genesis (Shakesby, 1997). Therefore, this letter aims to determine whether the terms ‘protalus rampart’ and ‘pronival rampart’ can coexist in literature by investigating the applicability of existing ‘diagnostic criteria’ that may be used to differentiate embryonic rock glaciers from pronival ramparts. A pronival rampart, formerly referred to as a protalus rampart, is defined as a ridge, series of ridges or ramp of debris formed at the downslope margin of a perennial or semi-permanent snow bed, which is typically located near the base of a steep bedrock slope in a periglacial environment (Shakesby, 2004). Shakesby (1997) highlights that pronival ramparts are mostly viewed as separate, independently produced forms of modified talus occurring in a nondevelopmental morphological continuum of unmodified talus, but other researchers (e.g. Haeberli, 1985) argue that ramparts represent part of a linear developmental continuum of rock-glacier and moraine formation. Stemming from the work of Haeberli (1985), Scapozza and others (2011) have recently proposed that the term ‘protalus rampart’ be used to define small permafrost creep phenomena (embryonic rock glaciers). The alternative usage of the term ‘protalus rampart’ by Scapozza and others (2011) within the new genetic definition of active rock glaciers as the visible expression of cumulative deformation by long-term creep of ice/debris mixtures under periglacial conditions (Berthling, 2011) may, in theory, allow the term ‘protalus rampart’ to coexist with ‘pronival rampart’. However, the morphological similarities of pronival ramparts and incipient or immature rock glaciers make it difficult to distinguish between these features in the field. Pronival ramparts are typically differentiated from embryonic rock glaciers through the identification of specific morphological and sedimentological characteristics (Hedding and others, 2010), but use of these ‘diagnostic criteria’ may prove inappropriate when differentiating embryonic rock glaciers from pronival ramparts. Curry and others (2001) indicate that well-developed protalus rock glaciers can be differentiated from pronival ramparts since these features are typically lobate in plan form, greater in length (downslope) than in width (acrossslope), exhibit a convex distal slope, terminate >70m from the talus slope and most distinctively they comprise meandering and closed depressions, downslope ridges and furrows, and transverse ridges and depressions. Many of these ‘diagnostic criteria’ are, however, inappropriate for the positive identification of embryonic rock glaciers since these features would lack many of the characteristics of welldeveloped protalus rock glaciers; making it extremely difficult to differentiate these features from pronival ramparts in the field. To further complicate the differentiation of pronival ramparts from embryonic rock glaciers, Shakesby (1997) highlights that, although rampart development is the result of supranival and subnival processes, pronival ramparts may also comprise permafrost and exhibit associated permafrost creep. Therefore, the identification of permafrost creep cannot be used to positively differentiate embryonic rock glaciers from pronival ramparts. In addition, Shakesby and others (1999) have identified snow creep as a subnival process responsible for pronival rampart formation, and snow creep may generate various morphological characteristics that may be exhibited by embryonic rock glaciers derived from permafrost creep. Thus this letter rejects the alternative usage of the term ‘protalus rampart’ to denote embryonic rock glaciers until such time as diagnostic criteria are identified by which pronival ramparts can be differentiated from other talus-derived landforms. Instead, it is suggested that ‘protalus rock glacier’ be used to denote embryonic rock glaciers. This is critical to avoid the incorrect identification and associated palaeoenvironmental inferences that have plagued research on pronival ramparts in the past; particularly since relict protalus rock glaciers could be used to infer former permafrost conditions whereas pronival ramparts do not require permafrost for their formation.

Diagnostic criteria for pronival ramparts : site, morphological and sedimentological characteristics

Abstract Pronival ramparts are discrete debris accumulations found below steep rock faces at the foot of snowbeds or firn fields but they are often confused with moraines, protalus rock glaciers or rock‐slope failure debris accumulations. This can be attributed to a poor understanding of the modes of rampart genesis, failure to recognise the significance of topography in their development and the use of inappropriate diagnostic criteria. Various characteristics have been suggested for identification of pronival ramparts but these are derived largely from relict features. Research on actively accumulating ramparts has shown that some of the suggested criteria are no longer useful. This paper reviews existing criteria and shows that, for diagnostic purposes, more emphasis should be placed on the attributes of actively accumulating features. A more robust set of criteria, derived from common characteristics of actively accumulating ramparts, are proposed that assists in discriminating relict and active pronival ramparts from other discrete bedrock cliff‐foot debris accumulations.

Formation of a pronival rampart on sub-Antarctic Marion Island

Abstract The formation of a pronival (protalus) rampart on sub-Antarctic Marion Island is investigated. Morphological attributes show debris at the angle of repose on the ramparts proximal slope and at a lower angle on the distal slope. Relative-age dating, based on the percentage moss cover and weathering rind thickness of the clastic component, indicates accumulation mainly on the proximal slope and rampart crest, implying upslope (retrogressive) accumulation. This contrasts with a previously published model for pronival ramparts, which proposes rampart growth by addition of material to the distal slope. Development of the Marion Island rampart is suggested to result from the control exerted by a relatively low-angled surface and a shrinking snowbed. A small debris step formed on the proximal slope appears to be a response to decreased snowfalls due to changing climate over the last c. 50 years. Growth rate of the rampart is considered to be variable during the Holocene in response to changes in climate and debris supply.

Spatial inventory of landforms in the recently exposed Central Highland of sub-Antarctic Marion Island

ABSTRACT Until recently, the Central Highland of sub-Antarctic Marion Island (above 750m a.s.l.) was covered by snow. Climatic amelioration is deemed responsible for the disappearance of the former permanent snowline which had a lower altitudinal limit of approximately 650m a.s.l. during the early-1950s. The recent sub-aerial exposure of this area now enables the geology and geomorphology to be documented. Mapping incorporated air-photo interpretation and field surveys using a hand-held Global Positioning System (GPS) to ensure spatial accuracy. Most grey lava outcrops above 750m a.s.l. exhibit some evidence of previous glaciations whereas black lava flows show no evidence of the effects of glaciers and must, therefore, post-date the Last Glacial Maximum (LGM). Frost processes currently predominate in the Central Highland, but there is a conspicuous lack of periglacial landforms (i.e. patterned ground) in scoria and grey lava areas. With the exception of thermal contraction cracking at one location, no other evidence for the development of geomorphological landforms in black lava areas exists. Other geomorphological landforms include meltout features, a manifestation of landscape process responses to climatic amelioration, mass movement landforms and the emergence of rudimentary aeolian landforms. Receding snow cover may enhance frost and aeolian processes, which could result in an interesting myriad of geomorphological landforms.

Aeolian processes and landforms in the sub-Antarctic: preliminary observations from Marion Island

Sub-Antarctic Marion Island has a hyperoceanic climate, with cold and wet conditions and consistently strong wind velocities throughout the year. Recent observations recognized the increasing role of aeolian processes as a geomorphic agent, and this paper presents the first data for transport by aeolian processes on a sub-Antarctic island. Data were collected through an intensive and high-resolution measurement campaign at three study sites using Big Spring Number Eight sediment traps and surface sediment samplers in conjunction with an array of climatic and soil logger sensors. Observed aeolian landforms are megaripples, and the data suggest that aeolian processes are also modifying solifluction landforms. The sediment traps and sediment samplers collected wind-blown scoria at all three study sites, and the annual (horizontal) aeolian sediment flux extrapolated from this preliminary data is estimated at 0.36–3.85 kg cm−2 y−1. Importantly, plant material of various species was trapped during the study that suggests the efficiency of wind for the dispersal of plants in this sub-Antarctic environment may be underestimated. This paper advocates long-term monitoring of aeolian processes and that the link between aeolian processes and synoptic climate must be established. Furthermore, wind as a means to disperse genetic material on Marion Island should be investigated.

Pronival ramparts: A review

Pronival ramparts are debris ridges formed at the downslope margins of perennial or semi-permanent snowbeds beneath bedrock cliffs. These landforms, also previously known as protalus ramparts, are located in periglacial environments, but the apparent simplicity of rampart formation made these landforms far less interesting than other modified forms of talus in cold environments. As a result, limited research, use of supposed relict examples and assumed formative mechanisms led to the misidentification of ramparts, circular arguments regarding genesis and inappropriate palaeo-environmental inferences. Several advances have, however, been made in the past few decades, particularly where actively-forming ramparts have been studied. Thus, this paper provides a review of research on pronival ramparts. In particular, focus is placed on the advances made in our understanding of rampart genesis, identification (diagnostic criteria) and palaeo-environmental significance. Notable advances include the development of a retrogressive model of rampart genesis to supplement the conventional downslope model of development, revised diagnostic criteria for field identification and the use of calibration equations during Schmidt-hammer exposure dating of pronival rampart. The use of pronival ramparts as palaeo-environmental indicators is also examined to determine what relict examples of these landforms may reveal about past climates.

The changing racial profile of academic staff at South African Higher Education Institutions (HEIs), 2005–2013

ABSTRACT South Africa has undergone transformation since the end of apartheid governance in 1994. Legislatively enforced, this transformation has permeated most sectors of society, including higher education. Questions remain, however, about the extent to which transformation has occurred in Higher Education Institutions (HEIs) in general, and across the academic staff body in HEIs in particular. In this study, we examine the transformation of academic staff profiles at HEIs throughout the country. Initially, we graph the racial profile of academics across multiple positions (junior lecturer to professor) from 2005 to 2013. We then use correlational analysis to identify which characteristics of universities in South Africa can be used to explain the racial inequities evident in South African HEIs. Our results indicate that world university ranking; percentage black African staff; percentage black African student body; and whether the university is ‘historically disadvantaged’, all influence the racial profile of the academic staff body to varying degrees. The size of the overall staff and study body does not appear to influence the racial profile of universities’ staff component. We conclude that transformation of the academic staff body of HEIs in South Africa is indeed occurring, albeit slowly. Rather than seeing this as a negative, we argue that the pace of ‘academic’ transformation in the country needs to be interpreted within the framework of academic governance.

Rock Mass Loss on a Nunatak in Western Dronning Maud Land, Antarctica

ABSTRACT This paper presents the first rock mass loss data for uncut clasts from continental Antarctica. A rock mass loss experiment using doleritic rock samples was conducted over a seven-year period, between 2008 and 2014, at the Vesleskarvet nunataks, Western Dronning Maud Land. The data show that approximately 10% of clasts suffered a mass loss that is an order of magnitude greater than the remaining 90% of clasts. Thus, the observed rock mass loss is suggested to occur in a series of events that are impossible to predict in terms of frequency and/or magnitude. However, extrapolating from the data obtained during the seven-year period indicates that rates of mass loss are slow and of the order of 1% per 100 years. Direct erosion by wind (including abrasion) as well as mechanical and chemical weathering are suggested to be responsible for rock mass loss. Rock properties, the weathering environment, and a lack of available moisture may be contributing factors to the slow rate of rock decay. This paper suggests that in this area of Antarctica, the slow rate of rock mass loss increases the longevity of existing periglacial landforms such as patterned ground and blockfields, but inhibits development of new patterned ground through the slow production of fines.

Campus Greening in Open and Distance Learning: Curriculum Initiatives in the Department of Geography, University of South Africa

This chapter presents and reflects on two campus greening initiatives by the Department of Geography at the University of South Africa (Unisa). The first initiative is the environmental management degree programme, which was implemented in 2000 as the first multidisciplinary, cross-faculty study programme offered at the institution. Successes and challenges as experienced with this programme and how they have been addressed will be reflected upon, with emphasis on implications for campus greening. The second initiative is the signature module “Environmental awareness and responsibility” implemented in 2012, which is available to any student from any discipline at Unisa. This module is part of a group of signature modules, offered exclusively online at Unisa. The reflection on this module will focus on implementation challenges in terms of the online offering, together with the extent to which the main thrust of the module has been achieved, namely to take students from “knowing” about sustainability to “doing” something for sustainability and thereby contributing to campus greening. The experience gained with these two initiatives points to a number of additional measures which can be embedded into the curriculum to achieve full engagement of students with reference to environmental sustainability within their local contexts. As an open and distance learning (ODL) institution, these measures could include the sharing of sustainable practices and experiences on an online platform. This will enable students and academic staff to generate and disseminate good sustainable practices between each other in such a way that both parties can become critical voices in a global but sustainable world. Moving from a contents-driven to an application-based approach to sustainability will contribute to a shift in the values and attitudes of successful graduates who will be able to apply the outcomes of the curriculum to strengthen localised innovation and sustainable practices in their living and working environments.