Plitvice Lakes National Park, a UNESCO World Heritage site located in Croatia, is celebrated for its stunning natural beauty, characterized by a series of turquoise lakes, cascades, and waterfalls. At the heart of this natural marvel is the geological process of karstification, alongside the biological activity that leads to the creation of natural dams, which play a pivotal role in forming the lakes.
Karstification is a geological process that occurs in areas with soluble rock, such as limestone, which predominates the bedrock of Plitvice Lakes National Park. Rainwater, slightly acidic due to dissolved carbon dioxide from the air and soil, percolates through the ground, slowly dissolving the limestone. This process creates distinctive landscapes characterized by underground rivers, caves, and sinkholes. Above ground, the dissolution of limestone contributes to the formation of the park’s complex hydrology, with water constantly emerging from the ground and flowing over the surface, creating the lakes and waterfalls.
The unique feature of Plitvice Lakes, distinguishing it from other karst landscapes, is the formation of natural dams, known as tufa or travertine barriers. This phenomenon is the result of biogeochemical processes involving the water’s high concentration of calcium carbonate from dissolved limestone and the role of algae, moss, and bacteria present in the water. As water flows over vegetation and rocks, these organisms trap and bind the minerals, leading to the precipitation of calcium carbonate. Over time, this process forms tufa barriers, which grow at a rate of about 1 cm per year. These natural dams are dynamic, continuously growing, breaking, and reforming, which leads to the ever-changing appearance of the lakes and waterfalls.
The water in Plitvice Lakes is renowned for its striking colors, ranging from azure to green, grey, or blue. The colors change constantly depending on the quantity of minerals or organisms in the water and the angle of sunlight. This natural interplay of light and water, combined with the geological and biological processes, creates the breathtaking landscapes of Plitvice Lakes National Park.
