Now draw the rock layers on the right set of blocks below, being careful to accurately display the rock thickness. Compare the map views of both cases. Part B. Folds. Folds are a type of plastic deformation that occurs in rocks. Folds develop in rocks that are naturally weak or in rocks that are deeply buried and thereby subjected to considerable heat and pressure.
Compression is the most common type of stress associated with folds.
There are 2 general forms of folds. Seldom are complete folds found in outcrops. Usually they are extensively eroded. If you erode an anticline, the map pattern will consist of parallel bands of rock layers with older rock layers exposed in the middle and younger rock layers to the outside. If you erode a syncline, the map pattern will consist of parallel bands of rock layers with younger rock layers exposed in the middle and older rock layers to the outside.