Fold

Rock layers are generally horizontal when they are initially formed, but under tectonic movements, they undergo bending and deformation due to stress, which is called folding. Anticlines and synclines are two basic forms of folds.

Here is a complex syncline, with its axis oriented northeast-southwest. The northwest limb is slightly steep, with a dip of 50°, while the southeast limb is gentler, with a dip of 40°. The core strata are strip-like limestones from 480 million years ago (Early Ordovician), and the limb strata are strip-like limestones from 500 million years ago (Late Cambrian).