Final answer:
The fold described in the given information is an anticline, which is formed when rock layers bend upward in an arch-like shape. The oldest rocks are in the center of the fold and the youngest rocks are on the outside.
Step-by-step explanation:
The fold described in the given information is an anticline. Anticlines are a type of fold where the rock layers bend upward forming an arch-like shape, with the oldest rocks in the center and the youngest rocks on the outside of the fold. The Sideling Hill fold in western Maryland formed due to the collision of Africa with North America, which caused compression and folding of the rock layers.