Introduction to the Sino-German Sisters Maar Lake Commemorative Plate: Huguangyan Maar Lake and Maar Lake in the Eifel region of Germany are both rare non-renewable geological resources in the world and are the focus of global paleoclimate and paleoenvironmental research. "Natural Almanac" and "Museum of Nature", the Eifel region of Germany is the origin of the study of Maar Lake in Europe and the world, and Huguangyan Maar Lake in Zhanjiang is the starting point of the study of Maar Lake in China. They are both world-famous volcanic geology Scenic area.