A syncline is a geological formation characterized by a downward-curving fold in rock layers. In a syncline, the youngest rock layers are typically found at the center, while older layers are located on the outer edges. This structure often forms as a result of tectonic forces that compress the Earth's crust. Synclines are commonly found in areas of mountain building and can be associated with other geological features, such as anticlines, which are upward-curving folds. Understanding synclines is important for geologists as they study the Earth's history and the processes that shape its surface.