 The central and southern regions near the Adriatic coastline and islands consist of low mountains and forested highlands.Natural resources found in the country in quantities significant enough for production include oil, coal, bauxite, low-grade iron ore, calcium, gypsum, natural asphalt, silica, mica, clays, salt, and hydropower.Karst topography makes up about half of Croatia and is especially prominent in the Dinaric Alps.