The two most common types of folds are

Anticlines and synclines.

Explanation:

This question is referring to geological folds that are formed from gigantic pressures that happen in a horizontal way, exerting a great force on rocks of more fragile compositions, such as sedimentary ones, this phenomenon allows the relief wrinkling.

There are several types of folds, however, the most common on the Earth's surface are called anticlines and synclines. The anticline type fold is a convex fold, containing old rocks, while the synclines type fold is a concave fold, containing new rocks.