Antony Mellor

Tafoni in the El Chorro area, Andalucia, southern Spain

Using a combination of field, laboratory and micromorphological evidence, this study examines tafoni (singular, tafone) in the El Chorro area of Andalucia, southern Spain, and makes inferences concerning the processes responsible for their formation. Twenty-five tafoni were randomly selected for field examination. The morphology of these cavernous rock domes is characterized by a helmet-shaped outer roof and an arched-shaped cavern, often with a partially overhanging visor; measurements of height, width and depth of the caverns revealed marked variations in size. The presence or absence of lichen cover, surface varnish, overhanging visor, cavern backwall stripes, rock flaking, weathering pits and cavern floor sediments was also noted. Surface hardness values, obtained using a Schmidt hammer, are relatively low but significantly higher on the outer roof of the tafoni than on the inner cavern walls. Analysis of sediment samples collected from the cavern backwalls and floors indicates predominantly sandy textures, alkaline pH values and some base cation enrichment. Micromorphological analysis of thin sections, prepared from undisturbed blocks, reveals large quantities of pore-filling cement, consisting mainly of calcite, mineral grains affected by weathering and pseudomorphic replacement, and dark, rounded nodules with a metallic appearance. In terms of their formation, different processes appear to act on different parts of the landform. On the outer roof surfaces, case hardening, resulting from near-surface cementation and surface varnish development, is dominant. On the inner cavern surfaces, however, core softening, resulting from granular disintegration and flaking, dominates. Exfoliation weathering, running water and wind deflation also appear to play an important role in tafone formation. A phased model of tafone evolution is proposed whereby the features pass through four phases of development–initiation, enlargement, amalgamation and degradation; in the study area there are examples of tafoni in each of these phases. Much of the evidence suggests that the tafoni are actively developing under current environmental conditions.

Experiential learning through integrated project work: an example from soil science

Abstract The planning, implementation and evaluation of an integrated soil science project are examined. The project aimed to develop a wide range of student‐centred approaches to learning, whilst promoting the development of a variety of transferable skills and personal qualities. The four project components (fieldwork, laboratory analysis, data interpretation and preparation of a written report) ran in sequence. Only the written report was formally assessed although potential developments of this system were considered. The project was implemented in the light of Kolbs cyclical model of experiential learning, and student evaluation was achieved through questionnaire analysis and group discussion.

Lead in the Soils and Stream Sediments of an Urban Catchment in Tyneside, UK

This paper focuses on lead contamination in topsoils and stream sediments of public access areas in a largely urban UK catchment. It compares severity of contamination with accepted trigger thresholds, examines spatial patterns relative to urban and industrial development, and explores potential mobility of lead using ‘plant available’: total lead ratios. Total and ‘plant available’ lead concentrations, organic content and pH were determined on 298 topsoil and 54 stream sediment samples using standard laboratory procedures. At the lowest total lead trigger threshold, approximately two thirds of topsoil and one third of stream sediment samples were contaminated. For ‘plant available’ lead the proportions were somewhat lower. The spatial pattern was characterised by ‘hot spot’ contamination, with highest values occurring in central and southern parts of the catchment which have a long urban and industrial history. Potential lead mobility is greatest in rural western and northern parts of the catchment where the lead fractions are probably derived from pedological alteration and weathering of soil parent materials. Conversely, in the urban and industrial areas, much of the lead probably consists of less mobile particulate forms. The implications of these findings for assessment, monitoring and management of contaminated areas are discussed.

Lead and zinc in the Wallsend Burn, an urban catchment in Tyneside, UK.

This paper examines lead and zinc concentrations in topsoils and stream sediments of public access areas in an urban catchment in Tyneside, UK. It examines the extent and severity of metal contamination, explores spatial patterns in relation to urban and industrial development, and makes inferences about potential metal mobility. Total and acetic-acid extractable lead and zinc concentrations, organic content and pH were determined on 121 topsoil and 22 stream sediment samples using standard laboratory procedures. Using the lowest trigger thresholds for total lead and zinc, almost 75% and 91%, respectively, of topsoil samples were classified as contaminated; proportions were rather lower for acetic acid extractable metals. Similarly, approximately 45% and 95% of stream sediment samples were contaminated with lead and zinc, respectively. The spatial distribution of metal concentrations was characterized by a hotspot pattern, with highest values in central and southern parts of the catchment where there is a long urban and industrial history. The potential mobility of zinc is considerably greater than that of lead in both topsoils and stream sediments, and for both metals is slightly higher in the stream sediments than in the topsoils; both of these differences are statistically significant (P < 0.05). The implications of the findings in this paper for assessment and monitoring of metal contaminated areas are explored.

Student-Produced Podcasts as an Assessment Tool: An Example from Geomorphology

The emergence of user-friendly technologies has made podcasting an accessible learning tool in undergraduate teaching. In a geomorphology course, student-produced podcasts were used as part of the assessment in 2008–2010. Student groups constructed radio shows aimed at a general audience to interpret and communicate geomorphological data within the context of relevant social and environmental issues. Questionnaire results suggest that the novel format engaged students, and promoted group working, IT, language and oral communication skills, and a deeper understanding of the context of geomorphic data. For teachers, podcasting technology offers efficient teaching of oral communication, with opportunities for distance and self-directed learning.

Determination of selected actinides (U, Pu and Am) in Belarus soils using high resolution inductively coupled plasma mass and gamma spectrometry

Depth distributions are presented for actinides and 137Cs in soils in agricultural areas of SE Belarus, where Chernobyl fallout levels of 90Sr and 137Cs in the soil have led to the land being taken out of habitation and agricultural use. Both gamma spectroscopy and high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) are used to provide absolute values of soil activity concentrations of U, Pu and Am isotopes, and also to provide isotope ratios. At our selected far-field locations (over 150 km from Chernobyl) the Chernobyl 137Cs fission product contamination levels are comparable (at c. 105 Bq kg−1) to those at our exclusion zone sampling site at 15 km from Chernobyl. The levels of transuranium isotopes at the far-field locations are, however, significantly lower, at below 2% of those observed in the exclusion zone site, whilst the levels of anthropogenic 235U are less than 10% of those naturally present. Our exclusion zone site, in October 2001, had a residual total surface deposition level of 239+240Pu of 23,780 Bq m−2, whilst the two far-field sites had 239+240Pu at levels of 190 Bq m−2 and 41 Bq m−2. The inhomogeneity of the transuranic isotope concentrations in these areas, and the decay of 241Pu to 241Am, may result in certain far-field locations with a long-term significant radiological hazard.

Diversifying assessment across the ‘Two Cultures’: student-produced podcasts in Geography

Abstract Since 2008, following growing collective interest in learning technologies and pedagogy, Geography and History departments at Northumbria and Newcastle Universities have successfully incorporated student-generated podcasting into a mixture of science, humanities and social science modules across all undergraduate levels. This paper presents a number of innovative examples using this approach, with the aim of promoting student creativity and analytical skills in ways different from traditional report- or essay-based assessments. It goes on to consider some of the advantages and challenges of this alternative assessment mode, from both student and tutor perspectives, across the science-humanities divide.

Soils and Environment

This text examines the ways in which soils are both influenced by, and themselves influence, the environment. It analyzes the propeties, processes and classification of soils, before discussing soils within the context of environmental history, and as components of natural environmental systems. Soil-human interactions are then examined in relation to landuse systems, environmental problems and management, soil survey and land evaluation.