Natural Arch

geology · erosion · landforms · nature's architecture

Rock gets sculpted. Natural arches form when rivers, ocean waves, or wind erode soft spots in cliffs and fins (tall, thin rock ridges). Over thousands or millions of years, these forces carve deeper and deeper until a tunnel opens right through the rock.

Water does the work. Coastal arches often form where waves crash against seaside cliffs, while inland arches appear where rivers flow through narrow canyons or where freezing water wedges into cracks and breaks the stone apart.

Famous and fragile. Some natural arches become famous landmarks like Delicate Arch in Utah. These stunning formations can last for millions of years, but they're always slowly eroding and occasionally collapse without warning.

Shapes tell stories. Each arch's shape reveals how it was carved. If it's smooth and rounded, flowing water probably sculpted it. If it's jagged and rough, weathering and cracking likely played a bigger role.