Sentinels of geography: legacy,public policy and contemporary relevance

Many geographers, past and present, have addressed public policy issues facing nations and peoples and in the process offered solutions to highly complex problems. Three ‘sentinels’ of the discipline, Halford Mackinder, Carl Sauer and Thomas Griffith Taylor, served as protectors of geography speaking up for the science in a way often confronting public officials, politicians and others. They contributed significantly to the development of geography in Britain, the USA, Australia and Canada, while engaging in public policy debates on topics such as geopolitics, geographical constraints on land use and natural resource management. All three were advocates for the unity of geography, stressing how an understanding of the interconnectedness of natural and human phenomena can assist in decision making. They were often frustrated by what they saw as ill-informed policies which did not respect geographic realities. Given their varied contributions, it is difficult to fully assess their impact both during their long and productive lifetimes, and subsequently, especially given the interdisciplinary and contested nature of their research. Today, academic geographers are faced with having to increasingly ‘prove the impact’ of their research, something beyond the comprehension of previous generations. Lessons from an analysis of the work of these ‘sentinels’, as well as my own experience, show how difficult a task this will be.     

Extension 3.0: Managing Agricultural Knowledge Systems in the Network Age

This article develops the idea of “Extension 3.0” as an approach to agricultural extension that capitalizes on the network structure of local agricultural knowledge systems. Over the last century, agricultural knowledge systems have evolved into networks of widely distributed actors with a diversity of specializations and expertise. Agricultural extension programs need to manage these networks in ways that maximize the synergy between experiential, technical, and social learning. Using empirical research from California farmers, we highlight the structure of these networks within and across contexts, and the importance of boundary-spanning relationships. We provide some initial recommendations about actions needed to realize the goal of Extension 3.0, which is to deliver relevant agricultural knowledge to the right people, at the right time and place.     

Hydrogeological origin of the CO2-rich mineral water of Vilajuïga in the Eastern Pyrenees (NE Catalonia,Spain)

The mineral water of Vilajuïga village in Alt Empordà (NE Catalonia, Spain) owes its uniqueness to an emanation of geogenic CO₂ that modifies groundwater hydrochemistry to produce a differentiated HCO₃–Na- and CO₂-rich groundwater among the usual Ca–HCO₃ type found in this region. A hydrogeological conceptual model attributes its occurrence to the intersection of two faults: La Valleta and Garriguella-Roses. The former provides a thrust of metamorphic over igneous rocks, formed during the Paleozoic, over a layer of ampelitic shale that, from a hydrogeological perspective, acts as a confining layer. The Garriguella-Roses normal fault, which originated during the Neogene, permits the degassing of geogenic CO₂ that is attributed to volcanic activity occurring in the Neogene. Groundwater mixing from the metamorphic and igneous rock units plus the local occurrence of CO₂ creates a HCO₃–Na water that still holds free-CO₂ in solution. Interaction with the gas phase is restricted at the intersection of the two faults. Radiocarbon dating, after correcting for geogenic dead carbon, estimates an age of 8,000 years BP. The low tritium content (0.7 TU) indicates that Vilajuïga water is a mix of “older” groundwater recharged in the metamorphic rocks of the Albera range and “younger” groundwater from the igneous rocks of the Rodes range, over a recharge area of 45 km² and a maximum elevation of 600 m. Given its origin as rare groundwater in the southern slope of the Eastern Pyrenees, purposeful monitoring is necessary to evaluate the groundwater vulnerability and anticipate impacts from nearby wells and climate-change effects.