Canyons & Gorges: How They Form & Where to See Them

A canyon forms when a river keeps cutting downward faster than the surrounding land erodes, usually because the land is being lifted at the same time. That combination — uplift plus downcutting — is why the deepest canyons sit on plateaus and in mountain belts rather than in flat lowlands. The result is a vertical slice through geological time: the rock at the bottom is always older than the rock at the rim.

How canyons & gorges form

The mechanism, without the jargon.

1. 01A river carries abrasive sediment and grinds its bed downward, a process called downcutting.
2. 02Tectonic uplift raises the surrounding plateau, so the river keeps cutting instead of meandering sideways.
3. 03Frost wedging and gravity widen the walls: water enters cracks, freezes, expands and prises blocks loose.
4. 04In dry regions, flash floods do most of the work in a few violent hours each decade, which is why deserts have such sharp, angular canyon profiles.

Best time to see them

Spring and autumn on almost every canyon. Summer brings dangerous heat at the bottom and, in the desert southwest, monsoon flash floods that arrive from storms many kilometres away. Winter closes high routes but gives empty viewpoints and low, golden light.

How to get there

Most famous canyons have a developed rim with roads, viewpoints and shuttle buses. Getting to the floor is a different proposition: it usually needs a permit, a guide, or both, and a descent that takes twice as long as you expect in the heat.

Tickets, permits & fees

National park entry is typically charged per vehicle and valid for about a week. Inner-canyon permits — for camping, hiking below the rim, or rafting — are separate, limited and allocated by lottery or a waiting list months ahead.

Notable canyons & gorges

Five worth building a trip around.

• Grand Canyon

  Arizona, USA

  1,800 m deep and 446 km long, exposing nearly two billion years of rock in its walls.

  April–May, September–October

• Colca Canyon

  Peru

  Roughly twice the depth of the Grand Canyon, with terraced walls still farmed on the slopes and condors on a reliable morning thermal.

  May–September

• Fish River Canyon

  Namibia

  One of the largest canyons in Africa, and one you can walk end to end in five days on a self-guided permit hike.

  May–September

• Slot canyons of the Colorado Plateau

  Utah, Arizona

  Narrow, sculpted passageways a shoulder-width wide, formed by flash flood scouring. Beautiful and genuinely lethal in rain.

  April–May, September–October Guide

• Tara River Canyon

  Montenegro

  Europe's deepest gorge, cut through limestone with water the colour of glacial milk and a road that hangs above it.

  June–September

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