Articles

Long-form explainers on the processes that build and reshape the Earth's surface, listed by most recently published.

• How Floodplains Develop

  A floodplain is the low-lying land bordering a river that is periodically covered by overflowing water, which deposits fresh sediment and gradually builds up the surrounding ground.

  Published February 10, 2026 · Reviewed February 27, 2026

• How Impact Craters Are Created

  Impact craters form almost instantly when a meteoroid, asteroid, or comet strikes a planetary surface at extremely high speed, excavating a circular depression far larger than the object itself.

  Published February 10, 2026 · Reviewed March 3, 2026

• Why Some Natural Landscapes Take Millions of Years to Form

  Natural landscapes form at wildly different speeds because rock hardness, the strength of the forces acting on it, and how continuously those forces act all combine differently from place to place, ranging from a single rockfall to tens of millions of years of mountain building.

  Published February 10, 2026 · Reviewed March 2, 2026

• How Rift Valleys Are Created

  A rift valley forms where tectonic plates pull apart, stretching and thinning the crust until a section of it drops down between parallel fault lines.

  Published February 9, 2026 · Reviewed February 27, 2026

• Permafrost Landscapes and Seasonal Change

  Permafrost is ground that stays frozen for at least two consecutive years, and the seasonal thawing and refreezing of the thin active layer above it shapes a distinctive set of cold-region landscapes.

  Published February 8, 2026 · Reviewed February 26, 2026

• How Sinkholes Form

  A sinkhole forms when an underground void, usually created by the slow dissolution of soluble rock, finally loses enough support that the ground above it collapses.

  Published February 7, 2026 · Reviewed February 26, 2026

• How Coral Atolls Develop

  A coral atoll forms when a fringing coral reef continues growing upward around a volcanic island that is slowly subsiding, eventually leaving only a ring of reef and low islands once the volcano sinks below the surface.

  Published February 6, 2026 · Reviewed February 25, 2026

• How Maps Represent Elevation and Relief

  Maps use contour lines, color elevation scales, and shaded relief to represent the three-dimensional shape of the land on a flat surface, letting a reader judge height, slope, and landform shape at a glance.

  Published February 5, 2026 · Reviewed February 27, 2026

• How Salt Flats Develop

  Salt flats form when water collecting in a closed desert basin evaporates repeatedly, leaving behind thick layers of crystallized mineral salts.

  Published February 5, 2026 · Reviewed March 1, 2026

• How Wetlands Form

  A wetland forms wherever land is saturated with water for long enough that it develops distinct waterlogged soils and water-adapted vegetation, whether beside a river, along a coast, or in a shallow basin.

  Published February 5, 2026 · Reviewed February 25, 2026

• How Sand Dunes Move and Change

  Sand dunes form when wind picks up loose sand and deposits it in mounds or ridges, which then migrate and change shape as wind conditions continue to act on them.

  Published February 4, 2026 · Reviewed February 24, 2026

• How Coastal Cliffs Develop

  Coastal cliffs form where waves undercut and weather exposed rock faster than it can be removed by gentler processes, leaving a steep edge that slowly retreats inland.

  Published February 3, 2026 · Reviewed February 24, 2026

• Plains and the Processes That Create Them

  Plains are large areas of relatively flat, low-lying land, built up by long-term sediment deposition, worn down from older uplands, or formed from layered lava flows.

  Published February 2, 2026 · Reviewed February 23, 2026

• Volcanic Islands vs Continental Islands

  Islands form in two fundamentally different ways: volcanic islands are built from erupted material above hot spots or subduction zones, while continental islands are simply fragments of continental crust left isolated by rifting or rising sea levels.

  Published February 2, 2026 · Reviewed February 25, 2026

• How Badlands Are Formed

  Badlands form where soft, sparsely vegetated sedimentary rock is carved rapidly by intense, infrequent rainstorms into dense networks of ridges and gullies.

  Published February 1, 2026 · Reviewed February 25, 2026

• How Plateaus Form

  A plateau is a broad, elevated area of relatively flat land, raised largely intact by tectonic uplift or built up from repeated layers of volcanic rock.

  Published February 1, 2026 · Reviewed February 23, 2026

• How River Deltas Develop

  A river delta forms where a river slows down and spreads out as it meets a sea, lake, or ocean, dropping the sediment it has carried and gradually building new land.

  Published January 30, 2026 · Reviewed February 22, 2026

• How Glaciers Shape the Landscape

  Glaciers are slow-moving rivers of ice that erode mountains into sharp ridges and carve valleys into broad troughs, while depositing the debris they carry along the way.

  Published January 28, 2026 · Reviewed February 21, 2026

• How Waterfalls Form and Change

  Waterfalls form wherever a river drops abruptly over a steep break in elevation, usually created by differences in rock hardness, and they continue to reshape themselves for as long as water keeps flowing over them.

  Published January 28, 2026 · Reviewed February 21, 2026

• How Deserts Form

  A desert forms wherever a region consistently receives very little precipitation, whether because of global air circulation patterns, distance from oceans, or the rain-blocking effect of mountains.

  Published January 26, 2026 · Reviewed February 20, 2026

• Natural Arches and the Power of Erosion

  Natural arches form when erosion and weathering hollow out a weak section of rock inside a narrow fin or headland, leaving a freestanding span that will eventually collapse under its own weight.

  Published January 26, 2026 · Reviewed February 21, 2026

• How Coastal Erosion Creates New Landforms

  Coastal erosion wears away exposed rock into cliffs, arches, and sea stacks, while the sediment it produces is carried along the shore to build new beaches, spits, and barrier islands elsewhere.

  Published January 25, 2026 · Reviewed February 20, 2026

• How Geysers and Hot Springs Work

  Geysers and hot springs form where groundwater is heated by volcanic activity close to the surface; only a rare few develop the underground plumbing needed to erupt on a cycle.

  Published January 25, 2026 · Reviewed February 22, 2026

• How Caves and Caverns Develop

  Most large caves form when slightly acidic water slowly dissolves soluble rock, usually limestone, carving out underground passages over thousands of years.

  Published January 24, 2026 · Reviewed February 20, 2026

• How Canyons Are Carved

  A canyon is a deep, narrow valley with steep walls, usually cut by a river into rock that is being slowly raised by tectonic forces.

  Published January 22, 2026 · Reviewed February 19, 2026

• How Fjords Are Created

  Fjords are deep, steep-walled coastal inlets carved by glaciers during past ice ages and later flooded by rising seas, leaving some of the most dramatic coastlines on Earth.

  Published January 22, 2026 · Reviewed February 19, 2026

• How Mountains Form

  Most of the world's great mountain ranges were raised by the slow collision of tectonic plates, then sculpted into peaks and ridges by ice, water, and wind.

  Published January 20, 2026 · Reviewed February 18, 2026

• How Valleys Are Formed

  Valleys are long, low-lying corridors between higher ground, most often cut by flowing rivers and later widened or reshaped by glaciers and shifting crust.

  Published January 15, 2026 · Reviewed February 10, 2026

• Karst Landscapes and Limestone Erosion

  Karst landscapes form when slightly acidic rainwater slowly dissolves soluble rock such as limestone, producing caves, sinkholes, disappearing streams, and sometimes dramatic rock towers.

  Published January 15, 2026 · Reviewed February 20, 2026

• The Main Types of Volcanoes

  Volcanoes take on several distinct shapes depending on how fluid their magma is and how violently it erupts, from broad shield volcanoes to steep stratovolcanoes, small cinder cones, and collapsed calderas.

  Published January 15, 2026 · Reviewed February 10, 2026