Special issue  

The study is a geomorphological analysis of Djebel Dahar, in south-eastern Tunisia, carried out as the basis for a UNESCO Global Geopark. We made a synthesis of the geographical, geological and geomorphological context of the area, proposed a delimitation for the future geopark, based on geological and geomorphological characteristics, and established a preliminary list of geosites, indicating their scientific value and their potential for geotourism.

In the field of regional geo-heritage promotion, this paper presents some opportunities, challenges and risks for geotope protection and geotourism.

Soil quality depends on water availability for plants. Sandy soils with a poorly permeable layer (fragipan) are considered inept for agriculture. However they are cultivated in Namibia as they secure a minimum harvest during droughts. In order to understand the hydrological influence of fragipans in these soils, soil moisture content was measured. The results illustrate that the combination of sandy topsoil and shallow fragipan has beneficial effects on plant-available water during dry periods.

The Monte Crenone rock avalanche of 1513 is well known on the southern side of the Alps because in 1515 it generated the largest inundation that has occurred in Switzerland in the Common Era, the Buzza di Biasca. New geological and historical observations allowed the setup of a numerical model of this major event, permitting a better definition of the chain of consequences that affected the alluvial plain of the river Ticino from Biasca to Lake Maggiore between the 16th and the 19th century.

The paper presents the results of recent geoarchaeological studies on the Ticino river alluvial plain. The sedimentological descriptions are combined with archaeological observations and constrained with radiocarbon dating. This approach, together with data from previous research and historical sources, provides an interesting overview of the eveolution of Ticino river morphosedimentary dynamics in relation to human settlements since the Neolithic.

Exposure ages make it possible to determine the time of weathering of a rock surface. They can be determined from rebound values measured with the Schmidt hammer and calibrated on surfaces of known age, defined in this study thanks to historical cartography and two mule tracks built in 300 and 1250 CE, which allowed us to reconstruct glacier fluctuations over the last 3 centuries in Val Scaradra and to define the time of deglaciation and rock glacier development in the Splügenpass region.

In mountain environments, active geomorphological processes have a strong influence on plant diversity because they act as renovators for habitats of pioneer species. In this paper, we propose criteria to assess the ecological value of dynamic mountain geomorphosites. We show that the interest of plant communities and the influence of geomorphological processes on plant communities are fundamental criteria for assessing ecological value in an exhaustive and objective way.

Soil erosion by wind and water is a commonly recognized phenomenon on agricultural land. Erosion in forests is studied less and generally considered to be limited because of the soil protection by vegetation. However, trees, when toppled because of old age or wind, loosen a considerable amount of soil when their roots are pulled from the ground. In addition, the holes left in the ground act as collectors for water and concentrated runoff, causing significant soil loss on forested slopes.

La riduzione del rischio, nelle aree poste in prossimità di pareti rocciose, mediante gestione dei sistemi di monitoraggio con finalità d'allerta evidenzia potenzialità, ma anche numerose criticità e limiti. L'articolo prende in esame due frane, originatesi da pareti rocciose, avvenute in prossimità di aree abitate nelle Alpi. Si analizzano costi ed efficacia sia delle opere di difesa sia dei sistemi di monitoraggio con funzione di early warning anche in relazione a soglie d'allerta e scenari.