The two small wetlands in the Putnok Hills were formed by landslides . The 1.8 ha Small Mohos Lake is approximately 15,000 years old and the 4 ha Large Mohos Lake is about 25,000 years old. The Mohos lakes are only influenced by precipitation and groundwater and have no hydrological connection with other water systems. The ponds have been slowly filled over the millennia, due to soil erosion and the vegetation that has grown on them. In the process, the layers of mainly peat moss have preserved the remains of the vegetation of the past, making the area of outstanding importance in terms of the history of vegetation.