The Quaternary Lancaster Sound trough‐mouth fan,NW Baffin Bay

The development of the Lancaster Sound Trough Mouth Fan (TMF) and glacial history in Arctic Canada were studied using a high‐resolution seismic profile across the entire fan and two piston cores. Stacked tills separated by erosion surfaces on the shelf pass seaward through till deltas into thick transparent glacigenic debris flow (GDF) deposits on the slope, separated by thin, well‐stratified glaciomarine layers. An age model was built by ties to the Ocean Drilling Program Site 645. The deepest GDF on the seismic profile was indicative of the onset of shelf‐crossing glaciation in the Early Pleistocene. The transition of the growth of Lancaster Sound TMF from an aggradational sequence (unit M) to an aggradational–progradational sequence (unit F) occurred at the Middle Pleistocene transition in glacial cyclicity. In the most recent glacial cycle, GDF sheets were deposited during Heinrich events 4 and 2 according to the correlation of the main detrital carbonate beds in two piston cores. The outmost till wedge reflects the maximum advance of the grounding glacier, far seaward of previously proposed Last Glacial Maximum ice extent. Copyright © 2011 John Wiley & Sons, Ltd.     

Electrical current along balloon rigging line inside thunderstorms

We have designed a new instrument to measure the current flowing along balloon rigging line during flights through thunderstorms. This instrument was tested in a high voltage facility and used to collect line current data during one balloon flight into a thunderstorm. Using these data, worst-case calculations are made; as such, we claim that they are the upper limits of any alteration (to the measured electric field or particle charge) that may occur, and the real number is likely much less. It is postulated the rigging-line current could have two separate effects on the measured electric field: (1) reduction of the field due to emission of corona ions, and (2) enhancement of the field due to the insertion of a long thin ‘conductor.' Even with current as high as 1 μA (the largest measured was around 50–100 nA), these two effects were found to be about −1% and +1%, respectively. Also, the calculated worst-case alteration to charged precipitation measurements is about 0.1 pC. Thus, with proper efforts to make the rigging line as poor a conductor as possible, it seems that we are justified in stating that these effects are negligible.     

The Application of Telemetry to Large-Scale Horizontal Anisotropic Permeability Determinations by Surface Tiltmeter Survey

An advanced two-way radio link (transceiver units) and data logging system have provided a powerful means of real-time series data collection and analysis. The application of this telemetry system to surface tiltmeter surveys provides significant cost savings for testing and analysis of deep, large-scale horizontal anisotropic permeability and heterogeneity determinations.
The determination of horizontal anisotropic properties requires one pumping well and eight to 10 tiltmeter monitoring stations. The validity of the depth of the test may reach 4,000 feet below land surface. With the addition of one partially penetrating observation well, the entire three-dimensional anisotropic permeability can be determined. With the addition of a fully penetrating well, the storage coefficient can be determined as well as leakage property (including vertical permeability of the confining layers). An example test case was analyzed for horizontal anisotropic permeability with remarkable success despite relatively unfavorable detection conditions.
A thorough understanding of the geology overlying the aquifer system must be made in order to assess the applicability of the surface tiltmeter survey to large-scale horizontal anisotropic permeability determinations.     

Managing migration in the Greater Mekong Subregion: Regulation,extra‐legal relation and extortion

One major aim of the Greater Mekong Subregion (GMS) integration programme, supported by the Asian Development Bank (ADB), is to foster regional ‘community’ for sharing resources, people and financial flows. This ‘community’ is the target of both economic growth and poverty reduction. The emphasis on ‘community’ in the ADB's mushrooming quantity of documents raises important questions about what kinds of people are included, in what roles and with what kinds of support and protection. This paper explores these questions in relation to the political economy of regulating ethnic migrants from Myanmar working in Thailand. This paper argues that extra‐legal relations between migrants and state/para‐state agents constitute a crucial part of regulation. In transferring the regulation of migration to the national scale, the ADB inadvertently reinforces national differences between Thais and cross‐border people. Additionally, the complicated and fluctuating implementation of national regulations in both countries leaves migrants subject to violence and extortion from state and quasi‐state agents in Thailand. This paper shows that the dynamics of global capitalism require ‘deportable labour’ supplied by ethnic migrants who are included in the GMS community as the most invisible, vulnerable and exploited members.     

Field observations of stratified atmospheric flow above an obstacle

In a study using the plume from the Four Corners power plant, near Farmington, N.M., lee waves were observed during times when the plume flowed across the Hogback. Wavelengths were typically about 1.2 km; wave amplitudes were more variable, ranging from 20 to 100 m. The observed amplitudes imply an obstacle that is broader and shallower than is actually the case. This is in agreement with laboratory studies that show the existence of regions of complex flow both upstream and downstream from an obstacle, which have the effect of broadening the region over which laminar flow occurs. Visual observation, measurement of the plume cross-sectional area both upstream and downstream from the Hogback, and measurement of plume aerosol concentrations show that turbulent and eddy flow over and downwind from the Hogback increase the rate of mixing of the plume with the surrounding atmosphere. This in turn increases the rate at which plume components come into contact with the ground.     

Towards a volcanic–structural balance: relative importance of volcanism, folding, and remobilisation of nickel sulphides at the Perseverance Ni–Cu–(PGE) deposit, Western Australia

Perseverance is a world-class, komatiite-hosted nickel sulphide deposit situated in the well-endowed Leinster nickel camp of the Agnew–Wiluna greenstone belt, Western Australia. The mine stratigraphy at Perseverance trends north-northwest (NNW), dips steeply to the west, and is overturned. Stratigraphic footwall units lie along the western margin of the Perseverance Ultramafic Complex (PUC). The PUC comprises a basal nickel sulphide-bearing orthocumulate- to mesocumulate-textured komatiite that is overlain by a thicker, nickel sulphide-poor, dunite lens. Hanging wall rocks include rhyodacite that is texturally and compositionally similar to footwall volcanic rocks. These rocks separate the PUC from a second sequence of nickeliferous, E-facing, spinifex-textured komatiite units (i.e. the East Perseverance komatiite). Past workers argue for a conformable stratigraphic contact between the PUC and the East Perseverance komatiite and conclude that the PUC is extrusive. This study, however, clearly demonstrates that these komatiite sequences are discordant, implying that the PUC may have intruded rhyodacite country rock as a sill with subsequent structural juxtaposition against the East Perseverance komatiite. Early N–S shortening associated with the regional D_I deformation event (corresponding to the local D_P1 to D_P3 events at Perseverance) resulted in the heterogeneous partitioning of strain along the margins of the competent dunite. A mylonite developed in the more ductile footwall rocks along the footwall margin of the PUC, while isoclinal F₃ folds, such as the Hanging wall limb and Felsic Nose folds, formed in low-mean stress domains along the fringes of the elongated dunite lens. Strata-bound massive and disseminated nickel sulphides were passively fold thickened in hinge areas of isoclinal folds, whereas basal massive sulphides lubricated fold limbs and promoted thrust movement along shallowly dipping lithological contacts. Massive sulphides were physically remobilised up to 20 m from their primary footwall position into deposit-scale fold hinges to form the 1A and Felsic Nose orebodies. First-order controls on the geometry of the Perseverance deposit include the thermomechanical erosion of footwall rocks and the channelling of the mineralised komatiitic magma. Second- or third-order controls are several postvolcanic deformation events, which resulted in the progressive folding and shearing of the footwall contact, as well as the passive fold thickening of massive and disseminated sulphide orebodies. Massive sulphides were physically remobilised into multiple generations of fold hinges and shear zones. Important implications for near-mine exploration in the Leinster camp include identifying nickeliferous komatiite units, defining their three-dimensional geometry, and targeting fold hinge areas. Fold plunge directions and stretching lineations are indicators of potential plunge directions of massive sulphide orebodies.     

The agricultural utility of lithic-mulch gardens: Past and present

The mulching of agricultural fields and gardens with stones, pebbles, volcanic ash and similar lithic materials is a variant agricultural strategy uniquely suited to the constraints of a dryland environment. While the agricultural literature contains reports on limited experiments with stone or gravel mulch, data regarding the employment of lithic mulch are lacking. This paper works to bridge this gap by comparing empirical data collected from prehistoric pebble-mulch gardens in the Galisteo Basin (New Mexico) to contemporary agricultural experiments with lithic mulch. Such past-present and experimental-real world comparisons allow us to more fully address the effectiveness of lithic mulching as an agricultural strategy. It is affirmed that lithic mulch is applied to garden plots, especially during periods of drought, in order to reduce soil erosion from wind and water, increase soil temperature to extend the growing season, increase water infiltration, and reduce the evaporative loss of water from wind and sun. The cumulative effect of this soil and water conserving technique is an increase in crop biomass and crop yield.     

Clostridium perfringens as a potential indicator for the presence of sewage solids in marine sediments

Marine sediment cores collected from several depths of water and distances from a California sewage outfall were tested to see if sediments influenced by sewage solids were a reservoir of enteric pathogens, and if concentrations of indicator bacteria were related to the presence of sewage solids. Vertical distributions of microorganisms in marine sediments were determined; there was a decrease of indicator bacteria with increasing sediment depth. Aeromonas was randomly isolated, but none of the enteric bacterial pathogens or viruses were detected. While classic indicator bacteria were of little value in predicting the presence of pathogens, or relative amounts of sewage solids, Clostridium perfringens may be a suitable indicator. Clostridium perfringens concentrations were not related to the presence of pathogens in sediments.