The recent sinkholes in northern Lithuania, specifically around Biriai and Pasvalys, show that there has been recent karst activity in the area. From 1995 to 1999, 84 new sinkholes appeared in the villages of Karajimilkis and Mantagaililkis. The three largest sinkholes were found in Pasvalys. These sinkholes are a result of karst processes in the gypsiferous layers of the Tatula Formation. The sudden appearance of sinkholes and ground subsidence can be dangerous, especially in urban areas, as they can cause damage to buildings. The presence of new sinkholes indicates a very sensitive engineering geological environment.