- Crust rocks are subjected to weak compressional forces. A series of small folds form on the crust. Later, the same crustal rocks are subjected to stronger compressional forces. These leads to the formation of an anticline and a syncline. On top of each now exists a series of
smaller anticlines and synclines. The anticline complex is called the anticlinorium, while the
synclinal complex is called the synclinorium