Tectonic implications of some field relations of the Adelaidean Cooee Dolerite,Tasmania

Complex contact relations between thin sills of the Adelaidean Cooee Dolerite and the enclosing flysch sediments (Burnie Formation) indicate emplacement of the sills into substantially uncompacted quasi‐liquid sediments very shortly after deposition. The sills are consequently coeval with the sediments rather than synchronous with the first phase of folding of the sediments (the Penguin Orogeny).

The K/Ar date on the Cooee Dolerite, here revised as 725 ± 35 m.y. (J. Richards, pers. comm.), very probably provides an estimate of the age of the sediments, rather than the age of the orogeny. Age relationships of the Cooee Dolerite, its host sediments and their deformation proposed hitherto can no longer be regarded as settled. The Burnie Formation may be part of a passive continental margin to the Rocky Cape Block, which was deformed during the Cambrian as a result of subduction beneath the active margin of the Tyennan Block.     

Church-based social capital, networks and geographical scale: Katrina evacuation, relocation, and recovery in a New Orleans Vietnamese American community

This research examines the role of social capital and networks to explain the evacuation, relocation, and recovery experiences of a Vietnamese American community in New Orleans, Louisiana in the aftermath of Hurricane Katrina. As the single largest community institution, the parish church’s complex bonding and bridging social capital and networks proved particularly critical in part because of its historically based ontological security. The process of evacuation, but especially relocation and recovery, was dependent on deploying co-ethnic social capital and networks at a variety of geographical scales. Beyond the local or community scale, extra-local, regional, and national scales of social capital and networks reproduced a spatially redefined Vietnamese American community. Part of the recovery process included constructing discursive place-based collective-action frames to successfully contest a nearby landfill that in turn engendered social capital and networks crossing ethnic boundaries to include the extra-local African American community. Engaging social capital and networks beyond the local geographical scale cultivated a Vietnamese American community with an emergent post-Katrina cultural and political identity.     

On the modelling of sand bedforms using the semivariogram

This study shows the usefulness of the semivariogram for modelling sand ripples created by water flows of varied flow intensity. A combination of two mathematical functions is fitted to each sample semivariogram, that is an exponential (or stochastic) component and a periodic component. The parameters of each of these components have direct physical meaning. A non-dimensional ratio combining the two parameters of the exponential model is interpreted as a regularity index (which increases with the degree of regularity of bedform arrangement). This regularity index is inversely related to the Froude number of the flow. The non-dimensional wavelength, estimated from the dominant periodic function, is also inversely and closely related to the Froude number. The wave height, accurately estimated from properties of the two fitted components, is a direct function of flow velocity and is also proportional to the standard deviation of bed elevations. The bedform shape introduces a considerable discrepancy between the generally assumed normal frequency distribution and the empirical distributions of bed height. The series of bed elevations are generally characterized by a mixture of normal distributions having the same variance but different means. The calculation of a covariance assuming a constant and single mean (as in spectral analysis) can therefore be misleading and the problem may be avoided by using the semivariogram.     

Toxicity in benthic freshwater cyanobacteria (blue‐green algae): First observations in New Zealand

Toxic cyanobacteria have been linked to dog deaths in the Waikanae River (1998) and Mataura River (1999 and 2000), New Zealand. These were Oscillatoria‐like species which formed benthic mats. This is the first time in New Zealand that animal deaths have been linked to toxins from benthic cyanobacteria.     

A requiem for the IFQ in US fisheries?

Despite their apparent economic benefits to harvesters, individual fishing quotas (IFQs) have only been adopted in three US fisheries: Mid-Atlantic surf clam and ocean quahog; South Atlantic wreckfish; and, North Pacific halibut and sablefish. During the 1996 reauthorization of the Magnuson-Stevens Fishery Conservation and Management Act, Congress temporarily blocked implementation of additional IFQ programs in US fisheries. In this paper, we argue that because of the emergence of an alternative, the cooperative, it is unlikely that new IFQs will be adopted in federally managed US fisheries. From an economic perspective, cooperatives offer the advantage of eliminating production externalities that may remain under an IFQ program with relatively large owner classes. More significantly, development of IFQ programs appears to be increasingly overwhelmed by the proliferation of both equity concerns and seemingly interminable rent-seeking behavior — both issues that can effectively block adoption of IFQs. Ironically (and paradoxically?), by reducing the scope of the equity issues acknowledged, the cooperative alternative narrows the pool of claimants and modifies the behavior of the remainder, making implementation more likely. A further irony exists in that IFQs are widely thought to be best designed at the local/regional level while part of the appeal of the cooperative model is that it appears to shortcut the often protracted nature of the local/regional political process by relying on direct intervention from Washington, DC, in the form of actions by Congress or the Justice Department.     

Setting new thermal standards for transitional and coastal (TraC) waters

The construction of a new generation of coastal power stations in the UK and other western European countries has highlighted the absence of robust standards for thermal discharges to transitional and coastal waters. The proposed discharge volumes are greater than hitherto, yet there has been little independent critical examination of their potential impact, whilst much of the existing guidance has been adapted from freshwater practice. This review considers the available knowledge on the tolerance and behaviour of fish and other marine biota to heated effluents. Appropriate ways are suggested of grouping fish species to reflect their sensitivity to thermal effects. The plethora of existing standards are considered and their validity assessed in a framework of predicted seawater temperature rise. Those species or groups of organisms most likely to be affected are identified and finally specific recommendations for thermal standards consistent with long term sustainability are proposed.     

Transneptunian Binaries

The discovery of binaries among the population of transneptunian objects isa landmark advance in the study of this remote region of the solar system.Determination of binary orbits will enable direct determination of systemmasses, fundamental for determination of density, internal structure, and bulkcomposition. The mere existence of binaries with the observed separations andapparent masses constrains models of planetary formation.     

Shape preferred orientation of object populations: automatic analysis of digitized images

An automatic technique is presented for systematic shape preferred orientation (SPO) analysis of crystal fabrics in rocks. This technique is based on digitization of an image with a CCD camera and separation of an object population from its matrix. The image is analysed globally using a rotating grid that is superimposed on the square pixel grid of the computer screen. The parametric method is based on counting intercepts in all directions. The interceps rose provides information on both the orientation and strength of the SPO. Problems of hardware-related counting noise anisotropy are avoided using an original method of filtering the intercept function with a linear, sliding mask on the counting grid. The technique was tested both on single objects of different shapes and on different populations of identical objects. A very high degree of accuracy was obtained for orientation measurements. Fabric shape parameters are introduced which are specific to this intercept technique; they compare favourably with shape parameters used in axial fabric analysis.     

Testing the suitability of geologic frameworks for extrapolating hydraulic properties across regional scales

The suitability of geologic frameworks for extrapolating hydraulic conductivity (K) to length scales commensurate with hydraulic data is difficult to assess. A novel method is presented for evaluating assumed relations between K and geologic interpretations for regional-scale groundwater modeling. The approach relies on simultaneous interpretation of multiple aquifer tests using alternative geologic frameworks of variable complexity, where each framework is incorporated as prior information that assumes homogeneous K within each model unit. This approach is tested at Pahute Mesa within the Nevada National Security Site (USA), where observed drawdowns from eight aquifer tests in complex, highly faulted volcanic rocks provide the necessary hydraulic constraints. The investigated volume encompasses 40 mi³ (167 km³) where drawdowns traversed major fault structures and were detected more than 2 mi (3.2 km) from pumping wells. Complexity of the five frameworks assessed ranges from an undifferentiated mass of rock with a single unit to 14 distinct geologic units. Results show that only four geologic units can be justified as hydraulically unique for this location. The approach qualitatively evaluates the consistency of hydraulic property estimates within extents of investigation and effects of geologic frameworks on extrapolation. Distributions of transmissivity are similar within the investigated extents irrespective of the geologic framework. In contrast, the extrapolation of hydraulic properties beyond the volume investigated with interfering aquifer tests is strongly affected by the complexity of a given framework. Testing at Pahute Mesa illustrates how this method can be employed to determine the appropriate level of geologic complexity for large-scale groundwater modeling.