See how forces inside Earth raise peaks and erosion reshapes them.
Mountain ranges record millions of years of moving plates, rising magma, shifting faults, weathering, and erosion.
Continents push together and thicken the crust.
Learn MoreLayers of lava and ash build around vents.
Learn MoreCrustal blocks rise as faults move.
Learn MoreCompression bends layers into ridges.
Learn MoreWater, ice, and gravity carve new forms.
Learn MoreUplift and wearing away continue together.
Learn MoreWhen tectonic plates converge, rock can crumple, fault, and thicken. Colliding continents built ranges such as the Himalayas, while oceanic crust sinking beneath a continent helps form other mountain belts. Movement is slow, but over millions of years it can raise enormous areas.
Magma reaching the surface erupts as lava, ash, and rock fragments. Repeated eruptions pile material around a vent, producing volcanic cones or broad shield mountains. Erosion may later expose the solidified channels that once carried magma upward.
When Earth's crust stretches, it can break along large faults. Some blocks tilt or rise while neighboring blocks drop, creating parallel ranges and basins. Steep fault scarps soften over time as streams and landslides carry rock downhill.
Rock layers under sustained compression can bend into folds instead of simply breaking. Upward arches and downward troughs may extend for many kilometers. Erosion slices through these structures, revealing repeating bands and producing ridges where resistant rock remains.
Rain, rivers, glaciers, freezing water, wind, and gravity wear mountains down. Streams cut valleys, glaciers carve broad troughs, and landslides move entire slopes. Eroded sediment travels to plains and oceans, while sharp peaks gradually become lower and rounder.
Formation and erosion happen at the same time. A range may continue rising even as material is removed from its surface. Geologists study rocks, fossils, earthquakes, and satellite measurements to reconstruct this history and measure changes still occurring today.