Fold in which the oldest rock layers are in the center?

The fold in which the oldest rock layers are exposed in the center is called an "anticline." In an anticline, the rock layers are arch-shaped, with the oldest layers at the core and progressively younger layers on the flanks. This geological structure is often formed by compressional forces that cause the earth's crust to buckle upward. Anticlines are important in the study of geology as they can indicate the presence of oil and natural gas reservoirs.