Jurassic lagoon: salt or soup?

The 140-million-year-old Solnhofen lithographic limestone of Bavaria, famous for the remarkable preservation of the earliest bird, Archaeopteryx, is one of the most acclaimed fossil horizons on Earth. Understandably, interest has focused on the more glamorous fossil finds from these rocks; the most common macrofossil, a small sea lily, has been neglected. However, this unprepossessing animal is a key player in the Solnhofen story .     

End-signature of deep-marine basin-fill, as a structurally confined low-gradient clastic system: the Middle Eocene Guaso system, South-central Spanish Pyrenees

The ca 300 m thick Guaso system is the youngest part of the ca 4 km thick deep-marine fill of the Middle Eocene Ainsa basin, Spanish Pyrenees. It is overlain by 150 to 200 m of fine-grained slope, prodelta and deltaic sediments. The ca 25 discrete deep-marine sandbodies within the Ainsa basin accumulated over ca 10 Myr, making eustasy the most likely control for coarse sand deposition (probably the ca 400 kyr Milankovitch mode). The first-order control on basin-scale accommodation, however, was tectonically-driven subsidence. Previously, the Guaso sandbodies were interpreted as linked to deep erosional, canyon-like features, but here it is argued that they are laterally extensive sandbodies, built by lateral-switching of 3 to 10 m deep erosional channels, and confined only by basin structure during deposition. The Guaso system represents the end of deep-marine deposition in a structurally-confined, delta-fed, low-gradient clastic system. The critical end-signature of deep-marine deposition was a phase of differential tectonic uplift above the underlying (Boltaña) thrust creating a narrower and shallower basin morphology, thus allowing sedimentation to create a low-gradient clastic system. Then, the next eustatic sea-level fall was insufficient to permit the cutting of canyons or deeply-incised slope channels, as had been the case earlier when the topographic relief between shelf and basin was at least several hundred metres greater. Such low-gradient clastic systems may characterize the end-signature for the infill of other shallowing-up deep-marine basins where a tectonic driver on subsidence is removed and/or differential uplift/subsidence leads to reduced sea floor gradients, leaving eustasy and sediment flux as the principal control on sediment supply.     

A water balance study of the upper White Nile basin flows in the late nineteenth century

Abstract

A water balance model of the Nile is described, working in terms of dry season flows. The main use of the modelling studies was to extend flows back to the start of observations at Aswan in 1869, and hence to estimate the levels of Lake Victoria during the high flow event of the 1870s. New estimates of Lake Victoria levels and outflows for the period 1870–1895 are deduced, extending the length of the observed data for Lake Victoria by some 25%. Crucially, the analysis includes the major flood event of 1878, which historical evidence suggests was the highest since 1860 or earlier. The modelling results are compared with previous estimates and a detailed examination of historical evidence. Some prospects for future levels are considered, taking into account the reconstructed levels of the late nineteenth century.     

Government Intervention in the Muda Irrigation Scheme, Malaysia: 'actors', expectations and outcomes

At the dawn of the third millennium the problems associated with large-scale irrigation lie largely unresolved. The outcomes of government policies rarely correspond with expectations, leading to conflict and misunderstanding between federal governments, local agencies and farmers. This paper examines the mis-match of expectations between policy implementors and policy recipients in the implementation of one government policy (tertlary intervention) in the Muda irrigation scheme, Malaysia. The findings illustrate that this policy is not achieving the productivity increase or water saving expectations for which it was designed. Instead, tertiary intervention has increased the capacity of the farmers to unofficially control the distribution and supply of the water resource and to engage in off-farm productive and non-productive activities. This results in: a significant over-supply of water; the inefficient use of this supply; and a reduction in yields without a reduction in incomes. Importantly, tertiary intervention has enabled the farmers to diversify their livelihood strategies whilst retaining access to the rice-farming culture. The findings presented in this paper serve to illustrate the significance of 'actor'expectations on policy outcomes and agrarian change.     

The water balance of the Betwa basin,India / Le bilan hydrologique du bassin versant de Betwa en Inde

ABSTRACT

A study of the water balance of a basin in India, where the annual monsoon season of water surplus contrasts with a longer period of deficit, shows that estimates of soil moisture recharge and groundwater recharge may be obtained in these circumstances by comparing seasonal net rainfall with runoff on two assumptions: soil moisture recharge is constant from year to year, and groundwater recharge is proportional to runoff.     

The water balance of Lake Victoria

Abstract

Hydrogeological investigations have been carried out in rural parts of Guntur district, Andhra Pradesh, India where agriculture is the main occupation. Granite gneisses associated with schists and charnockites are the main lithological formations, which are overlain by black cotton soils. Groundwaters are alkaline, very hard and mostly brackish. Possible sources of fluoride (F^?) are weathering and leaching of F^?-bearing minerals under the alkaline environment. A high rate of evapotranspiration, longer residence time of waters in the aquifer zone, intensive and longterm irrigation, and heavy use of fertilizers are the supplementary factors to further increase the F^? content in the groundwaters. The investigated area has been classified into three types with reference to concentration of ^F- prescribed for drinking: low-^F- (<0.60 mg l^?1), moderate-F^? (0.60–1.20 mg l^?1) and high-^F- (>1.20 mg l^?1). Forty-five percent of the total groundwater samples belong to the high-^F- category. Dental fluorosis is noticed in the region. A groundwater management programme is suggested.     

Natural and imposed injustices: the challenges in implementing 'fair' flood risk management policy in England

This paper examines the challenges facing English flood risk management (FRM) policy and practice when considering fair decision-making processes and outcomes at a range of spatial scales. It is recognised that flooding is not fair per se : the inherent natural spatial inequality of flood frequency and extent, plus the legacy of differential system interventions, being the cause. But, drawing on the three social justice models – procedural equality, Rawls' maximin rule and maximum utility – the authors examine the fairness principles currently employed in FRM decision-making. This is achieved, firstly, in relation to the distribution of taxpayer's money for FRM at the national, regional and local levels and, secondly, for non-structural strategies – most notably those of insurance, flood warnings and awareness raising, land use control, home owner adaptation and emergency management. A case study of the Lower Thames catchment illustrates the challenges facing decision-makers in 'real life': how those strategies which appear to be most technically and economically effective fall far short of being fair from either a vulnerability or equality perspective. The paper concludes that if we are to manage flood risk somewhat more fairly then a move in the direction of government funding of nationally consistent non-structural strategies, in conjunction with lower investment decision thresholds for other local-level FRM options, appears to offer a greater contribution to equality and vulnerability-based social justice principles than the status quo.     

CREATIVE DESTRUCTION AND TRIAL BY SPACE IN A HISTORIC CANADIAN VILLAGE*

Since the 1970s, stakeholders have attempted to revitalize selected rural communities across the developed world. The resulting initiatives have contributed much to the growing multifunctionality of rural space. Geographers have conceptualized this transformation in at least two ways: as a process of creative destruction and as a process of trial by space. In this article we demonstrate the merit of uniting these concepts to enhance our understanding of the evolution of historic towns and villages. We illustrate this unification in a study of Creemore, a picturesque village in the province of Ontario, Canada. Our analysis reveals that the transformation of this locale, from rural service center to heritage‐scape, has been fraught with controversy as various stakeholders have struggled to establish a dominant identity. We conclude that unification of these concepts does provide a useful framework for unraveling the evolution of historic communities within rural space.     

Cretaceous-Tertiary crossroads of migration in the Sahel

A series of expeditions undertaken over the last three years by a team of geologists from Kingston Polytechnic and the British Museum (Natural History) has increased our understanding of the Cretaceous and Tertiary palaeogeography of Central West Africa. The latest expedition discovered a dinosaur graveyard of Lower Cretaceous (Wealden) age. Studies of these and other fossils within the sedimentary rocks of the Iullemmeden Basin in Niger and Mali have shed new light on the Trans-Saharan Seaway migration route during the Cretaceous and Tertiary periods.