The Košana valley is a karst depression at the contact between Cretaceous and Palaeocene limestones from the NE with Eocene flysch layers to the SW. The central aim of our research is the geomorphological analysis of the Košana valley for the purpose od morphogenetic interpretation. The research was carried out on the basis of a detailed analysis of national and international scientific and professional literature, which served as the theoretical basis for our field research. The data obtained from official sources and our field research were analysed with the use of GIS tools. The present-day appearance of the surface of the Košana valley is the result of the simultaneous levelling and karstification of the the central part of the Košana valley, and neotectonic uplifting of the flysch bedrock in its south-western and southern area. The central part of the studied area is represented by a wide karst plain near the level of the fluctuating groundwater. Sušica, Stržen and Kulez-Farjavec streams have cut their channels into its bedrock. Sušica and its tributaries continued to cut through the flysch hilly ridge to the south, forming a narrow valley, which links Košana valley with the Reka valley. The Raša fault runs along the south-western edge of the study area. Along this fault, layers of Eocene flysch have been uplifted to form a hilly ridge, into which streams have carved a dense network of gullies and valleys. Steep and unlevelled longitudinal profiles of the valleys and the measurements of rate of uplift od the hanging wall block to the SW in the fault zone confirm the existence of active neotectonic uplift in the south-west and south of the Košana valley.
|
