A cliff is a prominent geological feature composed of rock that extends to a great height with a near-vertical, or sheer, face. Such formations are widespread in many types of terrain. They may occur along coastlines (as sea cliffs), in mountainous regions, or as the steep sides of canyons and gorges. Waterfalls often cascade over these rocky faces. The creation of cliffs is typically driven by natural mechanisms known as erosion and weathering. Weathering occurs when environmental forces, such as wind or precipitation, gradually disintegrate sections of rock.
In marine environments, intense winds and vigorous waves erode softer or more fragmented rock, leaving behind more resistant layers that stand as cliffs. The small fragments of rock produced by weathering are referred to as sediment or alluvium. Erosion is the process by which this material is moved from one place to another.
For coastal cliffs, this sediment typically settles on the ocean floor and is gradually dispersed by wave action. In the case of inland cliffs, sediment is frequently transported by flowing water or wind. Heavier fragments that break loose and fall are known as scree or talus. These accumulate at the base of many cliffs inland, forming what are termed scree slopes or talus piles. Some of these accumulations can become so extensive that soil and finer sediments collect between the stones, creating conditions where trees and other plants can take root and flourish.
Many geologists and climbers regard the Rupal Face of Nanga Parbat, a peak in the Himalayan range, as the tallest cliff on Earth. This immense wall ascends approximately 4,600 meters (15,092 feet) from its foundation. An alternative view holds that the eastern side of Great Trango, situated in the Karakoram range, is the world’s highest cliff. This rock face towers about 1,340 meters (4,396 feet) and is considered one of the planet's most challenging climbs. Both Nanga Parbat and Great Trango are located within Pakistan.
