Subsidy Removal and Farm-Level Stewardship in Northland

Illustrating one facet of farm-level environmental management in post-1984 New Zealand, this paper assesses changes in stewardship among Northland pastoralists. On-farm activities which protect or enhance the environment continue to be undertaken without state support. However, the withdrawal of environmental grants, in tandem with the wider agricultural policy changes, has reduced the propensity and ability of farmers to undertake stewardship, especially during cyclical downturns.     

Lambay, an ancient volcanic island in Ireland

Lambay is an island with a singular claim to distinction – a particular rock type. It has long been known as the source of the'Lambay Porphyry', a distinctive and decorative stone, grey–green in colour and full of small crystals of paler greenish feldspar. Commercial exploitation of this hard and attractive stone can be dated back to Palaeolithic times, when it was shaped into stone axes.     

From market to multifunctionality? Land stewardship in Australia

Recent assessments of Australia's land and water resources have revealed widespread patterns of serious decline, much of it directly associated with agricultural practices. The environmental degradation associated with agriculture has both biophysical and socio-economic underpinnings. While there have been calls to attend to the sustainability 'crisis' of Australian agriculture, policy settings remain firmly locked onto a productivist trajectory. We consider the implications of contemporary policy settings for farmland sustainability against the background of debates as to the meaning of 'multifunctionality'. The discussion is then turned to the Land Stewardship project, a strategic policy initiative within the State of Victoria that was looked to as a means of redressing environmental degradation in agricultural landscapes while also being attentive to rural community and economic issues. Towards the end of the paper we reflect on the question of how the Land Stewardship project aligns with theorizations of multifunctionality.     

Gravel antidunes in the tropical Burdekin River, Queensland, Australia

The geological record is punctuated by the deposits of extreme event phenomena, the identification and interpretation of which are hindered by a lack of data on contemporary examples. It is impossible to directly observe sedimentary bedforms and grain fabrics forming under natural particle-transporting, high-velocity currents, and therefore, their characteristics are poorly documented. The deposits of such flows are exposed however, in the dry bed of the Burdekin River, Queensland, Australia following tropical cyclone-induced floods. Long wave-length (up to 19 m) gravel antidunes develop during short (days) high-discharge flows in the upper Burdekin River (maximum recorded discharge near the study reach over 25 600 m³ s^?1 in February 1927). Flood water levels fall quickly (metres in a day) and flow is diverted away from raised areas of the river bed into subchannels, exposing many of the high-stage bedforms with little reworking by falling-stage currents. Gravel bedforms were observed on the dry river bed after the moderate flows of February 1994 (max. 7700 m³ s^?1) and January 1996 (max. 3200 m³ s^?1). The bedforms had wave-lengths in the range 8–19 m, amplitudes of up to 1 m with steeper stoss than lee faces and crest lines generally transverse to local peak-discharge flow direction. The gravel fabric and size sorting change systematically up the stoss and down the lee faces. The antidune deposits form erosive based lenses of sandy gravel with low-angle downstream dipping lamination and generally steep upstream dipping a-b planes. The internal form and fabric of the antidune gravel lenses are distinctly different from those of dune lee gravel lenses. The erosive based lenses of low-angle cross-bedded gravel with steep upstream dipping a-b planes are relatively easy to recognize and may be diagnostic of downstream migrating antidunes. The antidune gravel lenses are associated with thick (to 1 m) high-angle cross bed sets. Ancient antidune gravel lenses may be diagnostic of episodic high-discharge conditions and particularly when they are associated with high-angle cross-bedded gravelly sand they may be useful for palaeoenvironmental interpretation.     

Early Cretaceous Basaltic and Rhyolitic Magmatism in Southern Uruguay Associated with the Opening of the South Atlantic

The Early Cretaceous volcanic rocks of southern Uruguay comprisemafic and felsic volcanics. The position of these outcrops atthe southern edge of the Paraná–Etendeka continentalflood basalt province provides an opportunity to investigatepossible lateral variations in both mafic and more evolved rocktypes towards the margins of such an area of plume-related magmatism.The mafic lavas are divided into two compositionally distinctmagma types. The more voluminous Treinte Y Trés magmatype is similar to the low-Ti basalts of the Paraná floodbasalt province. The Santa Lucía magma type is a distinctand rare basalt type with ocean-island basalt type asthenosphericaffinities (high Nb/La, low ⁸⁷Sr/⁸⁶Sr_i). The felsic volcanicsare divided into two series, the Lavalleja Series and the AigüaSeries. The Lavalleja Series are chemically and isotopicallysimilar to the Paraná–Etendeka low-Ti rhyolites,and are considered to be related to the Treinte Y Tréslavas by extensive fractionation and crustal assimilation. TheAigüa Series have low ¹⁴³Nd/¹⁴⁴Nd_i and low ⁸⁷Sr/⁸⁶Sr_i andunlike the rhyolites of the Paraná, are interpreted asmelts of pre-existing mafic lower crust that subsequently underwentextreme fractionation. The differences observed in the felsicsuites may be linked to differences in the volumes of the associatedbasalts and the amounts of extension. KEY WORDS: South America; flood basalts; felsic volcanics; crustal melts; plume     

Rule-based spatial search

The application of applied artificial intelligence techniques to geographical data processing has attracted considerable interest in recent years as reflected in the research agendas of major GIS research institutions. This paper illustrates how a simple spatial problem, formalised using predicate calculus, may be readily implemented as a rule base in which the production rules represent Horn clauses. The theoretical significance of this exercise is the search for a high-level mathematical language capable of expressing, in a generic and implementation-independent syntax, the spatial relationships and queries typically handled by a GIS. Of more practical interest is the example it provides of mapping a conventional algorithm into a production rule knowledge structure.