In the past decade or so, though, there has been an explosion of cairns around the world—in national parks, in the Scottish Highlands, on the beaches of Aruba. Park rangers, environmentalists, and hikers have all become alarmed, to varying degrees. The movement of so many stones can cause erosion, damage animal ecosystems, disrupt river flow, and confuse hikers, who depend on sanctioned cairns for navigation in places without clear trails.
The posts found within the RockStacks and StoneStacking hashtags on Instagram range from amateurish a couple of stones against the backdrop of the ocean to seriously impressive round stones balanced improbably, or a sharp rock standing on end atop a pebble.
It is common for multiple stacks to appear in a single picture; they look like chimneys or gravestones or maybe the ruins of a lost civilization. Inspired by social-media posts, new rock stackers are taking up the hobby, and the piles of stones are proliferating along with the pictures of them. He first noticed the boom when he visited remote beaches in Orkney, Scotland, and found them littered with rock piles. Hourston and the Blue Planet Society decided to call attention to the ecological impact of stone stacking, wading into a contentious debate.
The stackers are accusing him of making mountains out of pebbles. National parks are caught in the crosshairs of the debate, too. The calamity of the stone stack, in our anxious times, seems admittedly minor.
Aesthetic fads can go global now, with strange consequences. Rock stacking has unfortunately grown into a widespread activity. All over the world, people are stacking rocks and stones in all shapes and sizes. This activity has made its way to Aruba as well. But why? Naturalist and conservationist opinions seem to point to this being a really bad idea to the point that many national parks and regions are banning it outright. The official uses of rock stacking are memorials or landmarks. Cairns have been used since the beginning of humanity, mostly to set marks to not get lost in nature.
Later, cairns were used as burial monuments and as landmarks to locate buried items. In Aruba, many people think the meaning behind stacking rocks is that you can make a wish. Rock stacking is something that we strongly advise against. An example of physical weathering is wind blowing across the desert playas.
This process causes rocks to form a specific pyramid-like shape and they are called ventifacts. Select from these resources to teach about the process of weathering in your classroom. Meet Walter, a friendly animal who will guide you on your quest for knowledge about erosion and weathering. You will begin your journey by doing different activities to that will simulate weathering and erosion. The game continues with a variety of activities and information. At the end, you will play a bonus arcade game to award you for your good work.
Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water.
A similar process, weathering , breaks down or dissolve s rock , but does not involve movement. Erosion is the opposite of deposition , the geological process in which earthen materials are deposited, or built up, on a landform. Most erosion is performed by liquid water, wind, or ice usually in the form of a glacier. If the wind is dust y, or water or glacial ice is muddy, erosion is taking place.
The brown color indicates that bits of rock and soil are suspended in the fluid air or water and being transported from one place to another.
This transported material is called sediment. Physical erosion describes the process of rocks changing their physical properties without changing their basic chemical composition. Physical erosion often causes rocks to get smaller or smoother.
Rocks erode d through physical erosion often form clastic sediments. Clastic sediment s are composed of fragments of older rocks that have been transported from their place of origin. Landslide s and other forms of mass wasting are associated with physical weathering. These processes cause rocks to dislodge from hillsides and crumble as they tumble down a slope.
Plant growth can also contribute to physical erosion in a process called bioerosion. Plants break up earthen materials as they take root, and can create cracks and crevice s in rocks they encounter. Ice and liquid water can also contribute to physical erosion as their movement forces rocks to crash together or crack apart. Some rocks shatter and crumble, while others are worn away.
River rocks are often much smoother than rocks found elsewhere, for instance, because they have been eroded by constant contact with other river rocks. Liquid water is the major agent of erosion on Earth. Rain, rivers, floods, lakes, and the ocean carry away bits of soil and sand and slowly wash away the sediment. Rainfall produces four types of soil erosion: splash erosion, sheet erosion, rill erosion, and gully erosion.
Gullies carry water for brief periods of time during rainfall or snowmelt but appear as small valley s or crevasse s during dry season s. Valley erosion is the process in which rushing stream s and rivers wear away their bank s, creating larger and larger valleys. The Fish River Canyon, in southern Namibia, is the largest canyon in Africa and a product of valley erosion.
Over millions of years, the Fish River wore away at the hard gneiss bedrock, carving a canyon about kilometers 99 miles in length, 27 kilometers 17 miles wide, and meters 1, feet deep. The ocean is a huge force of erosion. Coastal erosion —the wearing away of rocks, earth, or sand on the beach—can change the shape of entire coastlines. During the process of coastal erosion, waves pound rocks into pebbles and pebbles into sand. Wave s and current s sometimes transport sand away from beach es, moving the coastline farther inland.
Coastal erosion can have a huge impact on human settlement as well as coastal ecosystem s. The Cape Hatteras Lighthouse, for example, was nearly destroyed by coastal erosion. At the time, the lighthouse was nearly meters 1, feet from the ocean. Over time, the ocean eroded most of the beach near the lighthouse.
By , the pounding surf was just 37 meters feet away and endanger ed the structure. Many people thought the lighthouse would collapse during a strong storm. Instead, thanks to a significant engineering feat completed in , it was moved meters 2, feet inland.
The battering force of ocean waves also erodes seaside cliff s. The action of erosion can create an array of coastal landscape features.
For example, erosion can bore holes that form cave s. When water breaks through the back of the cave, it can create an arch. The continual pounding of waves can cause the top of the arch to fall, leaving nothing but rock columns called sea stack s. The seven remaining sea stacks of Twelve Apostles Marine National Park, in Victoria, Australia, are among the most dramatic and well-known of these features of coastal erosion.
Wind is a powerful agent of erosion. Aeolian wind-driven processes constantly transport dust, sand, and ash from one place to another. Wind can sometimes blow sand into towering dune s. Some sand dune s in the Badain Jaran section of the Gobi Desert in China, for example, reach more than meters 1, feet high. In dry areas, windblown sand can blast against a rock with tremendous force, slowly wearing away the soft rock. Wind can also erode material until little remains at all.
Ventifact s are rocks that have been sculpted by wind erosion. The enormous chalk formations in the White Desert of Egypt are ventifacts carved by thousands of years of wind roaring through the flat landscape. Ice, usually in the form of glaciers, can erode the earth and create dramatic landforms.
In frigid areas and on some mountaintops, glaciers move slowly downhill and across the land. As they move, they transport everything in their path, from tiny grains of sand to huge boulders.
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