Folds are one of the most common phenomena you can find in geology. A fold is usually produced by plainer layers (usually sedimentary rocks) which are curved by sympathetic efforts. The kind of folding in the photo below is called a Chevron and its main feature is that the angle of hinges is very acute, almost without curvature. The undoctored photo (below) is of a completely natural stone fold formation found in Greece. The image was found on Geologiaaldia's Instagram feed.