Prospekt Gea, Intresting facts

Photo 1. Loess on Susak Island (Photo by Nina Trinajstić)


Loess is a terrestrial sediment composed mostly of silt-sized particles (0.002 – 0.063 mm) in which grains of quartz prevail. It is formed by the accumulation of wind-blown dust. When in a dry state, the sediment is very stable but can easily collapse when wet. To prevent it from collapsing, islanders plant reeds along the margins to protect the material from further erosion. The largest areas of loess were formed in the Pleistocene but loess can also be found in sites from the Upper Carboniferous, the Triassic and the Miocene. Loess can originate from periglacial regions, deserts and mountainous regions. These are regions in which huge amounts of silt could form and be blown by the wind to a suitable accumulation site. Loess composed of material formed by glacial weathering is called periglacial loess. It formed in the Pleistocene during the glaciation, while paleosoil formed during times of glacial melting. The study of loess is important because it helps to determine the duration and age of glaciations and to identify changes in global atmospheric circulation.

Loess on the Kvarner islands was formed by the weathering of primary rock in the igneous and metamorphic regions of the western and central part of the Alps. The material was carried by the Po River to lowland areas and deposited on the alluvial plain that stretched all the way down to the Pescara-Šibenik line because of low sea levels during the Pleistocene. From the alluvial plain, the material was transported by the wind to higher regions with vegetation.

 Nina Trinajstić

Slika 2. Eolski sediment otoka Unije (foto: Velimir Ivačić)