Palaeoenvironmental reconstruction of the Milna valley on the island of Vis (Central Adriatic) during the late Holocene.

Abstract

This study provides a reconstruction of the 1.5 ka palaeoenvironmental evolution of the small, and presently dry, Milna valley on the island of Vis. Sediments from the valley were studied using multi-proxy approach, applying sedimentological, mineralogical, petrological, anthracological, malacological, 14C and land cover analyses, in regard to climatic, vegetation, and hydrological changes. The mineral composition of the siliciclastic detritus from the Milna valley points to the Dinaride Ophiolite Zone in Bosnia as its dominant source of origin, eroded by the Neretva River, and deposited in the form of alluvial sediments in the Central Adriatic area. However, Cetina and Drin Rivers may have also contributed some of the sediments. Regional aeolian resedimentation of the material occurred during Pleistocene, which later accumulated and became preserved in the Milna valley. Beside the Dinaride Ophiolite Zone, part of the mineral composition is influenced by minerals from the Alpine region and by neutral to basic volcanism, probably of Italian origin. During the Dark Age Cold Period (DACP) the Milna valley was covered by forests of the Pinus sylvestris group, within which cold-resistant and closed forest habitat preferring species (molluscs) lived. This forested environment probably lasted until the Little Ice Age (LIA) period when fires occurred in the 15th and 16th centuries. The opening of the landscape corresponded to the resettling of the population from the interior to the coast and to the expansion of vineyards on the island. The deforestation enabled the formation of torrential flows and deposition of unsorted sediments. Most of the pebbles are rounded clasts of the Middle Cretaceous (Cenomanian) dolomite in which the valley is formed. However, pebbles which are not present in outcrops of the Milna valley have also been identified. After the LIA, the valley became dry again and has been continuously under anthropogenic impact ever since. Different cartographic sources enable the further tracing of land cover changes from the beginning of the 19th century to present day. The analysis revealed that the highest anthropogenic impact on the landscape occurred in the second part of the 19th century, after which afforestation started. Moreover, the major issue today relates to changes influenced by the current relative sea level rise. This study adds to the knowledge on coastal fluviokarst valley evolution in typical Mediterranean conditions, relating our understanding of Holocene deposition, human activity, and land cover changes on the island of Vis.