Which geological feature is formed when a broader rock layer is compressed into an arch shape?

An anticline is a geological feature that is formed when rock layers are compressed and fold into an arch shape. This occurs due to tectonic forces acting on the Earth's crust, which can cause the rock layers, typically sedimentary in nature, to bend upwards. In an anticline, the oldest rock layers are found at the core of the fold, while younger layers are positioned on the flanks. This characteristic is important for geologists because it often indicates the potential locations of oil and gas reservoirs, as these structures can trap hydrocarbons.

In distinguishing an anticline from other geological features, it's essential to note that a syncline represents a downward-folding structure, where the youngest layers are in the center. A xenolith refers to a fragment of rock that is embedded in another type of rock, particularly in igneous contexts, and does not relate to folding. Angular unconformities occur when there is a significant time gap in the geological record, creating an angle between the layers due to tectonic movements or erosion, and are not formed by the same compressive forces that create an anticline.