Close to the village of Poljanska lies a site that used to be a shallow lake, a place that holds numerous time capsules―as leaves were covered by muddy sediment that turned into 'marlstone'. These historical capsules have been dated back to the Otnangian-period; 17 million years ago. Once opened they started to show a wide range of plant species, ranging from Eucalyptus to a early relative of modern-day cinnamon. It also served as crucial evidence that there once was a subtropical climate in Croatia ―nowadays impossible.
Part of: Geosites in Papuk