Michael Day

Disintegration of Fan Sediments in Death Valley, California, by Salt Weathering

In Death Valley, California, an area of high aridity and great salinity, alluvial fans de scend into the zone of salt accumulation. When the rounded fan gravels come into contact with salt, some of which is sodium sulfate, they are rapidly shattered and reduced in size. Silt and clay are formed by this salt weathering process and this fine material may be subject to deflation processes.

GML-Based Interoperable Geographical Databases

Many geographical databases have been developed for different programs and applications, but data acquisition and data sharing are still a big problem because no interoperability exists among these different databases. This study presents a GML (Geography Markup Language) approach to build a geographical database in order to enable interoperability. As an open, non-proprietary industry standard, GML overcomes the problems of current GIS software proprietary data models and database structures. Compared with other standards, such as the Geographic Data File (GDF) and Spatial Data Transfer Standard (SDTS), the GML approach has the advantage of enabling on-line data exchange. GML holds promise in providing a standard way to share and use existing spatial data over the World Wide Web. A GML-based interoperable geographical database for the conservation of the Stone Forest Landscape is implemented as a case study. It shows how the public can access and use the GML-based spatial database through a user-friendly interface and that GML can deliver high quality vector data on the Web.

Field survey and analysis of hillslopes on tower karst in Guilin, southern China.

Limestone dissolution in tropical and subtropical humid southern China created residual hills with steep slopes, a landform that is referred to as tower karst. Two types of tower karst landform feature, fenglin or peak forest (isolated towers) and fengcong or peak cluster (linked-base towers), were identified in Guilin. Previous studies proposed two hypotheses regarding their origin and evolution. One is the sequential evolution model from peak cluster to peak forest. The other is a parallel development model, which postulates that both peak cluster and peak forest have developed simultaneously. Through detailed field survey and analysis of slope forms on tower karst in Guilin, it was found that the mean slope angle of the towers is very high (62·4°) and ranges from 60° to 75°. There is no significant difference in mean slope angle and slope angle distribution between towers in the peak cluster basin and peak forest floodplain areas. Mean slope angle increases with intensified fluvial dissection. Three levels of caves in the towers of the peak forest in Guilin were identified in previous research. The isolated towers of the peak forest as well as scattered residuals of peak cluster are generally distributed in the centre of the Guilin syncline. Favourable circumstances of allogenic water concentration indicate that development of the peak forest resulted from the combined effects of subcutaneous and subterranean dissolution as well as subsequent collapse and recession by fluvial erosion after uplifting. By contrast, peak clusters generally occur on the limbs of the syncline or at the periphery of the Guilin basin with relatively higher elevations. The thick vadose zone and predominantly vertical flow suggests that peak clusters are mainly formed by the combination of intensive uplifting and the enhancement of original dolines. The evidence of slope survey and slope analysis suggests that both isolated towers and linked-base towers developed simultaneously but by different mechanisms of formation and different combinations of development processes. Copyright

Differentiating tower karst (fenglin) and cockpit karst (fengcong) using DEM contour, slope, and centroid

The complex geometry of tropical karst landforms poses particular challenges for morphometric analysis, morphological classification and evolutionary assessment. Detailed geomorphological studies of the two most spectacular forms—tower karst (fenglin) and cockpit karst (fengcong)—have employed time consuming and labor intensive field surveys, which have yielded inconclusive and ambiguous results. This paper tests a novel discriminatory approach utilizing contour, slope and centroid derived from the ASTER Global Digital Elevation Model to differentiate between cockpit and tower karst in the Guilin area of southern China. Morphological indices are calculated to compare and contrast geomorphic variations using Object-Based Image Analysis (OBIA). The results suggest that the method provides a feasible means of differentiating between tower and cockpit landforms, and that OBIA offers a fast and semi-automatic way to extract morphological parameters.

The Cockpit Country, Jamaica: Boundary Issues in Assessing Disturbance and Using a Karst Disturbance Index in Protected Areas Planning

The Cockpit Country is Jamaica’s only remaining pristine karst area and is perhaps the most significant karst landscape in the Caribbean. It may be a candidate for UN World Heritage status but its boundaries are contentious. The Karst Disturbance Index (KDI) is an important tool for karst conservation, providing an objective numerical measure of the extent to which karst landscapes have been disrupted by human activities. Its application is, however, constrained by issues of boundary determination and location, and the Cockpit Country exemplifies this phenomenon when different boundaries are determined on geomorphic, historical, existing, and proposed management criteria. Analysis of land use data from 1998, together with extensive field surveys, reveals that the measure of the extent of human disturbance is closely related to the positioning of the boundary, with the incremental inclusion of peripheral areas beyond the core forest reserve resulting in a dramatic increase in the disturbance index. Not only is this a methodological concern in using the KDI, but it also illustrates how the KDI may be useful in planning and establishing potential protected area boundaries.

Rotating-disc electrode voltammetry. The catalytic mechanism (EC′) and its nuances

The various mechanistic nuances of the catalytic (EC′) mechanism have been considered and it has been shown that steady-state rotating-disc voltammetry alone can discriminate between almost all of the various pathways considered. This deduction has been illustrated with reference to, first, the oxidation of the acetate anion in acetonitrile solution by means of the electrogenerated radical cation of tris(p-bromophenyl)amine and secondly, to the reduction of t-butyl bromide, in the same solvent, mediated through the radical anion of fluoranthene.

Resource use in the tropical karstlands of central Belize

Rural tropical ecosystems are subject to many traditional land uses that employ the indigenous karst resources: rock, water, soil, vegetation, and wildlife. Individual resource pressures often are subtle, but their combined impact can precipitate instability in the tropical karst environment, potentially resulting in disruption of food, water, and fuel supplies. The karst of central Belize was used intensively for some six centuries by Maya farmers, but between the 10th and 19th centuries AD most of it reverted to secondary forest. Commercial logging dominated the 19th and early 20th centuries, followed by the expansion of subsistence and commercial agriculture after 1945. In the 1980s resource use has accelerated as population and other pressures increase. Much karst remains forested, but there is increasing clearance for agricultural uses, particularly for citrus cultivation and small-scale mixed agriculture. Soil depletion has begun to occur, water resources are increasingly taxed, and some wildlife is threatened by habitat destruction and increased hunting. Lime production for the citrus industry has promoted quarrying, water extraction, and fuelwood use. Environmental stresses currently do not exceed the threshold of instability, but the rapidly developing rural economy warrants careful monitoring of resource pressures.

Loss of encephalitogenicity of a myelin basic protein-specific T cell line is associated with a phenotypic change but not with alteration in production of interleukin-2, γ-interferon or tumour necrosis factor

Continued stimulation of a CD4+ myelin basic protein-specific T cell line led to loss of in vivo encephalitogenic activity but no alteration in ability of the line to produce interleukin-2, gamma-interferon or tumour necrosis factor. Loss of encephalitogenicity was, however, associated with an increased presence of CD4+ CD8+ cells which likely represents preferential outgrowth of this population. The possible in vivo relevance of these findings is discussed.

CARBONATE EROSION RATES IN SOUTHWESTERN WISCONSIN

Between 1977 and 1979 three sets of erosional weight loss tablets were em-placed in the karst of southwestern Wisconsin to measure both potential and actual rates of carbonate erosion. Tablets of Jamaican White Limestone, which has been used in many other karst areas, were used to gauge relative erosion potential while tablets of the local bedrock, Prairie du Chien dolomite, were used to assess absolute rates. Tablets of Yugoslavian limestone were emplaced as part of a world-wide study of comparative rates. Tablets were recovered in 1983 and 1984. Although potential erosion rates are similar to those in other carbonate areas, the sluggish dissolution of the indigenous dolomite retards karst development. Soil cover increases erosion rates and rates at a given depth are consistent over sites of up to 10 m2. The highest erosion rates were recorded by the Yugoslavian tablets but betweensite variations caution that results based on a single site may be unrepresentative. Over 37% of all tablets were affected by...

Landslides in the Gunung Mulu National Park

investigate to what extent variations in erosion rates have been brought about by climatic change. At the beginning of the expedition, in August 1977, geologists had accumulated a good knowledge of the area, mostly because of the interest of oil companies since the Second World War. But our knowledge of the basic geographical data was limited: we had little idea ofthe variations of rainfall with altitude, nor of the hydrological characteristics of the Melinau and other rivers. Our first priority, therefore, was to acquire this basic information. Until this was done, work on the processes which are now affecting the landscape, and which are discussed in later papers, could not begin.