The fold where the youngest rock layers are in the center is called a syncline.

Here's why:

* Syncline: A syncline is a downward fold, like a trough or a U-shape. Since sediment layers are deposited in a horizontal fashion, the youngest layers are deposited on top, making them the center of the fold.

* Anticline: An anticline is an upward fold, like an arch. The oldest layers would be in the center of an anticline.