The subglacial record of northern Hudson Bay: insights into the Hudson Strait Ice Stream catchment

Ross, M., Lajeunesse, P. & Kosar, K. G. A. 2010: The subglacial record of northern Hudson Bay: insights into the Hudson Strait Ice Stream catchment. Boreas, 10.1111/j.1502‐3885.2010.00176.x. ISSN 0300‐9483. In this paper, we present new insights into the glacial dynamics and potential configuration of the Hudson Strait Ice Stream catchment in the northern Hudson Bay–western Hudson Strait region. Our reconstruction is based on new field observations and till compositional data from Southampton Island, remote sensing imagery and multibeam bathymetric data from the Hudson Bay sea floor, as well as on a re‐examination of previously published data from this vast region. Our findings suggest that, during the late Quaternary, the HSIS catchment consisted of a number of ice‐stream tributaries feeding a curvilinear trunk that potentially extended into western Hudson Bay. In contrast to previous interpretations, the occurrence of fluted bedrock hills, over‐deepened basins, Dubawnt erratics and carbonaceous till on the islands at the head of Hudson Strait is taken to imply that cold‐based conditions did not prevail on these islands. The upland area of Southampton Island and the surrounding channels played an important role in controlling the location of the main tributaries, with the higher central terrain forming a large inter‐ice‐stream zone lacking carbonate detritus. Coats Island contains abundant evidence of vigorous ice flow, such as mega‐scale glacial lineations (MSGLs). MSGLs also occur on the sea floor southwest of Coats Island but the sea‐floor imprint is highly discontinuous. Observations on the western Hudson Bay mainland show evidence of southeastward fast ice flow that is spatially consistent with the Dubawnt dispersal train. Despite the geomorphological discontinuities, this may indicate that the HSIS onset zone extended far inside the Laurentide Ice Sheet and across contrasting geological domains.     

Interstadial and last interglacial deposits covered by till in Scotland: comments and new evidence

A section of the recent paper on 'The last Scottish ice-sheet: facts and speculative discussion' by J. Brian Sissons ( Boreas , Vol. 10, pp. 1–17) is commented upon. New dating and stratigraphic evidence from northeast Scotland is also presented.     

Islam in Sydney: Contesting the Discourse of Absence

Non‐recognition is one of the key modes of re‐inscribing the Other. In Sydney's anti‐mosque politics this form of oppression was manifest as a discourse of absence. Sydney Muslims have been portrayed as non‐existent within, or external to, localities where mosques have been proposed. In these circumstances claims to belonging and citizenship by Sydney Muslims have been fundamentally injured. Census data are used to challenge the historical and contemporary constructions of Islamic absence in Australia. Sydney Muslims are a culturally diverse and somewhat disparate faith group. They are increasingly present in areas outside of the initial zones of residential focus. This diversity and dynamism is a substantial challenge for Islamic community building (Ummah) in Sydney and presents rich foci for further research.     

Sedimentation in an actively tilting half-graben: sedimentology and stratigraphy of Late Tournaisian–Viséan (Mississippian, Lower Carboniferous) carbonate rocks in south County Wexford, Ireland

The Wexford Basin (south-eastern Ireland) is a NE–SW-trending sedimentary basin containing carbonates and evaporites deposited during the Late Tournaisian and Viséan. Two separate depositional areas are defined on the basis of facies and facies associations. Sediments were deposited in inner ramp, lagoonal and peritidal environments near Rosslare, and in a more open-marine, shallow- to moderately deep-water, mid to outer ramp environment in the western area around Duncormick. Thick breccia deposits that occur in the Wexford Basin formed as a result of (i) fault movement that produced syn-sedimentary debris flows in the Late? Chadian (Breccia type I); (ii) dissolution of anhydrite/gypsum and subsequent collapse of sedimentary strata (Breccia type II); and (iii) fracturing and brecciation of porous rock caused by the movement of high temperature, late diagenetic fluids along fault planes (Breccia type III). The NE–SW facies polarity displayed by both sedimentary successions was the result of NW–SE extension and the reactivation of the NE–SW-trending Wexford Boundary Fault during the Chadian. Extension at the SE margin of the basin with downthrow to the NNW gave the basin a half-graben character. Thickening of the debris flow deposits to the SW suggests that while the half-graben was being tilted it also underwent a NE–SW block rotation due to an axial component of that normal fault.     

A test of TOPMODEL'a ability to predict spatially distributed groundwater levels

TOPMODEL was calibrated to a small catchment using precipitation and runoff data. Acceptable fits of simulated and observed runoff were obtained during both the calibration and validation periods. Predictions of groundwater levels using this calibration did not agree well with observations at the 37 points within the catchment where groundwater levels were measured, including three locations with continuous recordings. Groundwater level observations at one single point in time, however, sufficed to calibrate new topographic–soil indices that improved the prediction of the local groundwater levels at the observed tubes. This suggests that spatially distributed calibration data are necessary to exploit reliably TOPMODEL's ability to predict spatially distributed hydrology. The mean or recalibrated transmissivity values at these 37 points differed from the catchment mean as determined by the precipitation–runoff calibration. Thus, while groundwater information can help in predicting groundwater levels at specific locations, increasing the number of local groundwater level measurements is not sufficient to improve the spatially distributed representation of subsurface flow by TOPMODEL for the catchment as a whole, as long as the groundwater information is not integrated in the precipitation–runoff calibration. © 1997 John Wiley & Sons, Ltd.     

Is asymptotic non-divergence of the large-scale tropical atmosphere consistent with equatorial wave theories?

Observations suggest that the large-scale tropical atmospheric circulations, associated with intraseasonal variabilties, are dominated more by the vorticity than the divergence. The present paper examines the consistency of the above observations with linear equatorial wave theories. Both free and forced linear waves are considered. The free equatorial waves are classified into two major categories: (1) the Rossby waves, strongly dominated by vorticity and (2) the inertial-gravity waves, relatively dominated by the divergence. Both the Kelvin and the mixed-Rossby gravity waves are intermediate of these two major categories.
In the forced case, the wave response is predominantly inertial-gravity wave-like for periods less than 5 d, thus predominantly divergent. On the other hand, for forcing with the longer periods, the wave response closely following free Rossby-wave structures, asymptotically approaches to a non-divergent state. The asymptotic tendency for non-divergence is found to be much stronger than observed. The difference is so stark that, notably, the tropical intraseasonal variability cannot be consistent with linear equatorial waves theories.     

Stable oxygen isotope and pollen records from eastern Scotland and a consideration of Late-glacial and early Holocene climate change for Europe

The presence of marl deposits belonging to the Lateglacial period in a former lake basin at Lundin Tower in Fife, Scotland has allowed palaeoenvironmental investigations by means of carbonate δ¹³C and δ¹⁸O, and organic matter δ¹³C, in addition to palynology. The variations that emerge reveal strong similarities between the pollen and isotope records and these are interpreted as reflecting climatic shifts. The classic Late-glacial pattern of Oldest Dryas–Bølling–Older Dryas–Allerød–Younger Dryas may be evident and other climatic oscillations are shown to have occurred not only during the Allerød but also in the Preboreal. The problem of the time discordance between isotopic change and pollen representation is addressed through explanations involving lags in plant colonization. A comparison of the δ¹⁸O records from 43 sites across Europe reveals two different regional patterns, which raises fundamental questions over the nature of Late-glacial palaeoclimates.