The type of fold where the oldest rock layers are in the center is called a syncline.

Here's why:

* Syncline: A syncline is a downward fold in rock layers, shaped like a trough or a "U". The youngest rocks are typically found at the edges of the fold, and the oldest rocks are in the center, at the bottom of the trough.

* Anticline: An anticline is an upward fold in rock layers, shaped like an arch. In an anticline, the oldest rocks are found at the crest (top) of the fold.

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