A foreland basin is a structural depression that forms adjacent to a mountain range, resulting from the flexure of the lithosphere due to the weight of the mountain belt. These basins are filled with sediments eroded from the mountains and are key features in understanding the processes of mountain building, sedimentation, and basin evolution.
Source DeCelles, P. G., & Giles, K. A. (1996). Foreland Basin Systems. Basin Research.