Buckle folds are extremely common. They form when layers are compressed along their length. These structures have been studied for many years. You can even make your own - by squeezing plasticene layers in a vice or between your hands. To follow the mechanics of buckle folds - start here. This sequence looks are simple buckles of single layers. But rocks contain many layers and these can interact. To see these effects, including how parasitic folds may form, click here. However, if layering is very intense, folds develop with highly angular hinges - kinks. You can see this by clicking here. Alternatively you can return to the mechanics front page.