(iDa qualche anno, Stonline intrattiene dei contatti con la Dry Stone Walling Association (DSWA) in Inghilterra. info : http://www.dswa.org.uk. ) Tutti i collaboratori della Stonline hanno superato esami a differenti livelli di prestazione presso esperti dell'associazione DSWA. Questa cooperazione attiva è rappresentata da progetti in Svizzera e in Scozia. Dieter Meier (in marzo), Daniel Mettler (in giugno) e Urs Lippert (in settembre) hanno lavorato durante quest'ultimo anno con diverse altre persone per differenti progetti. Come punto culminante, è stato costruito un ponte da Norman Haddow e Dieter Schneider nel marzo 2003.

Altre immagini:www.bigstoneman.freeservers.com

Stoneline will be there

32. International Geologcial Congress, Firenze, Italy

Marcel Stalder, Department of Geology, University of Stellenbosch South Africa
Daniel Mettler, Stoneline, Switzerland

Dry stone walls are a characteristic feature of many European cultural landscapes. The technique of dry stone masonry developed due to the general availability of natural stone as building material and the high cost of transporting mortar and cement to remote areas. The walls were constructed for a diversity of purposes and as such give testimony to a long tradition of man to cultivate and develop its natural environment. The most common type of walls are field walls and retaining walls, which subdivide pastures and support the typical terraced landscapes of many parts of Europe. In addition, dry stone walls act as foundations and provide support against erosion, floods and avalanches.
The aim of this contribution is to illustrate the influence of geology on the construction, appearance and stability of dry stone walls in selected areas of Europe, including Switzerland, the Aegean Islands and Southern Italy. Since the building material for the construction of dry stone walls is generally taken from a local source, the walls commonly reflect the ambient geological environment. In geologically heterogeneous regions, such as the Alps or the Aegean Islands, the geological diversity is often manifested by the presence of irregular and colourful random walls. In contrast, the geologically homogeneous Jurassic of Switzerland and the study area in Southern Italy are characterised by the occurrence of long and regular limestone walls. The physical characteristics of the rock influence the way building stones can be dressed and shaped. These prerequisites thereby control the building technique and ultimately the appearance and durability of the wall. Preferred building stones are competent rocks with planar internal structures (bedding and cleavage planes, joints), such as well-cemented sandstone, limestone and marl. The latter can be dressed into rectangular stones with good faces, which allow the construction of well-coursed regular walls. Hard and compact rocks, such as granite, massive gneiss and unjointed basalt, shatter unpredictably when dressed with a hammer or cannot be shaped at all. These stones result in the construction of irregular random walls. Apart from the quality of construction, the long term stability of dry stone walls is dependent on the resistance of the material against weathering. Collectively, the geological prerequisites thus control the beauty but also the deterioration of dry stone walls.