The Alleghenian Orogeny was a significant mountain-building event that occurred during the late Paleozoic Era, around 325 to 260 million years ago. It primarily resulted from the collision of the ancient continents of Gondwana and Laurasia, which formed the supercontinent Pangaea. This collision caused extensive folding, faulting, and uplift of the Earth's crust, leading to the formation of the Appalachian Mountains. The orogeny is characterized by various geological features, including metamorphic rocks and sedimentary basins. It played a crucial role in shaping the geology of the eastern United States, particularly in regions like Pennsylvania and West Virginia. The effects of the Alleghenian Orogeny can still be observed today in the landscape and rock formations of these areas.