Editorial to the Special Issue “urban use of rocks” in Environmental Earth Science

Abstract

Urban rocks are so diverse that it is common for geology students to be forced on field trips along the streets of university towns and cities. They joke that this is simply to save money, but in reality the stone of the urban fabric has often been carefully gathered, is finely polished and presented at a convenient elevation. It reflects a balance between the availability of suitable local stone and the important decorative and durable character of materials brought from greater distances. This book includes the description (Perez-Monserrat et al. 2012) of the Geomonumental Route project undertaken by the Instituto de Geologia Economica of CSIC (Spain) and Istituto per i Beni Archeologici e Monumentali of CNR (Italy), which explores the Madrid bridges’ route over the Guadarrama river built with granitic material from the Guadarrama mountains and a route via the 16th century coastal towers of the Apulia region in southern Italy. The volume collects chapters about urban geology that arose out of presentations within Monuments under threat, a session that was part of the General Assembly of the European Geosciences Union in Vienna, April 2012. These chapters present the outcomes of recent research that has examined the choice, testing, exposure and sensitivity of building stones to the urban environment. As such it should be valuable for those undertaking research and studying the geology of our urban fabric. Traditional aggressive air pollutants have been decreasing in cities, but they have left thick black crusts from the late 20th century (Gulotta et al. 2012). However, even low sulphur dioxide concentrations can lead to observable deterioration (Graue et al. 2013) and the rate of attack can seem proportionately faster as deposition when concentrations are low (Wiese et al. 2012). While sulphur dioxide and smoke from coal has been decreasing, the effects of traffic-related pollutants, nitrogen dioxide and particulate matter, are particular apparent along busy streets (Auras et al. 2013). These environments, less polluted by sulphur but rich in nitrates can encourage biological growth and freshly cleaned surfaces can be rapidly recolonized (Hallmann et al. 2012). Improved air quality has led to interests in other mechanisms of damage such as the changing levels of moisture (Stuck et al. 2013), perhaps associated with secondary porosity (Doncel-Lopez et al. 2012) or expansion processes in volcanic tuff rocks (Wedekind et al. 2012). It is likely that climate change may cause water to penetrate more deeply into porous stone (McCabe et al. 2013). There has been a heightened interest in salt weathering through S. Siegesmund (&) Geoscience Center, University of Gottingen, Goldschmidtstr. 3, 37077 Gottingen, Germany e-mail: ssieges@gwdg.de