In geology, a fold that forms with rock layers arching upward is known as what?

In geology, a fold that forms with rock layers arching upward is referred to as an anticline. This structure occurs when the earth's crust experiences compressive forces, causing the layers of rock to bend and rise in an arch-like formation. Anticlines typically have the oldest rock layers at their core, with progressively younger layers flanking them on either side. Understanding this concept is critical in geology, particularly in structural geology and in the study of oil and gas reserves, since anticlines can often serve as traps for hydrocarbons.

The other terms represent different geological features: a syncline is a type of fold that bends downward, creating a trough, while downfold and uplift describe broader geological processes rather than specific structures of rock layers.