Sinkholes form when underground cavities cause the surface above to collapse

The massive sinkholes of China

Parts of China's limestone-rich terrain is fertile ground for massive caves, where some of the world's largest sinkholes are located. Hidden away in dense, lush forests, geologists are frequently discovering new sinkholes to explore. This piece...

Deep-sea trenches form when one tectonic plate subducts another underwater

Oceanic plates sink when colliding with less dense continental plates, bending the seafloor into steep depressions that can be almost 11 kilometers deep. Many of Earth’s strongest earthquakes occur at these plate boundaries, often featuring volcanic activity.

Speleothems are diverse mineral formations that form in air-filled caves

Speleothems like stalactites and stalagmites form when water deposits minerals after a cave rises above the water table and fills with air. These formations preserve the mineral deposits, which may serve as climate proxies, for as long as a million years.

Fossils form in environments where dead organisms can be rapidly buried

Such landscapes enable corpses to be encased by terrain before significant decay occurs. They are most commonly found in river deltas and sinking coastal regions, where sediments accumulate over time until geological forces expose the areas to erosion, revealing embedded fossils.

Since the Industrial Revolution, surface ocean waters have become 30% more acidic due to the absorption of carbon dioxide.

Geode formation begins with trapped gas bubbles in igneous or sedimentary rock

Over thousands or millions of years, water seeps into the cavity created by the bubble and deposits minerals, which slowly build and crystallize into quartz, agate, amethyst or other crystals.

When oceanic plates sink beneath tectonic ones, they can generate magma

At converging oceanic-continental plate boundaries, the subduction of the oceanic plate introduces seawater that reduces the melting temperature of the overlying mantle. This causes it to melt into less dense magma, which can rise to fuel more volcanic activity.

Manholes connect underground sewer and water drain pipes

Wherever a portion of sewer is connected to another, a manhole is built. These serve both as access points for maintenance and as connectors for the system. This video shows how crucial manholes are for proper sewer functioning.

Tectonic earthquakes are caused by tectonic plates sliding past one another at fault zones, deforming rock through friction as energy builds like a stretched rubber band.

View examples of rift valleys, the product of surface divergent boundaries

At these boundaries, tectonic plates move apart, stretching and thinning Earth’s crust as long valleys are formed from smaller, interconnected valleys and troughs. Ongoing rifting and erosion can further sink the valley, becoming a rift lake if volcanic activity becomes inactive.

Most volcanic activity occurs in submarine volcanoes on the seafloor

At divergent plate boundaries in mid-ocean ridges, volcanic activity produces new ocean crust as the seafloor spreads. These areas are home to underwater mountains with extensive biodiversity due to redirecting ocean currents and concentrating food for marine life.

The ocean gets its salt from runoff carrying fragments of eroded rock and from seawater dissolving salts and minerals from magma at seafloor spreading centers.

While landslides are associated with the downward flow of unstable terrain, the term encompasses a variety of geological processes, which are distinguished by how the material moves and what materials are involved.

Why are ancient ruins underground?

When cities fall into disrepair, it's often easier to flatten what you can and build on top. This is why modern archaeologists frequently discover ruins underground, revealing generational layers of cities rebuilt over time. This video explores major examples of this principle, from ancient Troy to even modern Seattle.

Enhanced geothermal power systems can trigger earthquakes by injecting fluid into rock, increasing subterranean pressure.

Explore an interactive map of global water gaps, caused by human consumption surpassing the rate at which water reserves are replenished by the hydrologic cycle.

The simplicity of immersed tube tunnels

Tunnels have traditionally bored holes through the earth below the water. On the other hand, immersed tube tunnels connect hollow, massive sections in trenches along the floor of the body of water. Each section is built on land, floated to the site, submerged, and connected. This method saves money by reducing expensive underground work, and it preserves an area's aesthetic appearance.

Geological features on Mars' surface provide evidence of massive past flooding

The presence of river valleys, enormous canyons, and other structures carved by water on Earth suggests that water flowed abundantly across Mars' surface. The layering of rocks in the walls of these structures indicates the intensity and volume of these flows.

After a landslide, repeat activity may follow the appearance of cracks, springs of water, or dirt, sand, and rocks tumbling down from scars—exposed portions of Earth where the initial landslide began.

Explosive volcanic eruptions happen when magma pressure overcomes rock strength

Magma usually stays underground because of a balance between its upward pressure, the weight of the Earth’s crust above, and the crust’s rock strength. Landslides can reduce crust weight, while built-up gas pressure can strengthen magmastatic pressure.

Some tectonic plates move faster than their underlying convection currents

Like a chain slipping off a ledge, as tectonic plates sink, their weight can pull the rest of the trailing plate forward, accelerating their movement. Plates can also break apart and fall, creating a suction effect that drives movement, resembling leaves following a passing car.

Carbon sinks absorb more greenhouse gases than they produce

The largest on Earth are oceans, which capture 25% of all carbon emissions and 90% of excess atmospheric thermal radiation while generating half of the world's oxygen. Wildfires and deforestation have reduced forests' net sink capacity, though fungi are believed to capture and store over a third of global carbon emissions.

In the US, flash floods—rapid floods that occur within six hours of rain—kill more people than tornadoes, hurricanes, and lightning.

How diamonds form in the deep earth

Deep within Earth's mantle, diamonds form from carbon-bearing fluids. The formation of these beautiful gemstones, the only direct samples we have of the mantle, helps scientists uncover how carbon functions deep inside our planet. Understanding this complex process aids in the exploration for new diamond deposits.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

The Devil's Hole pupfish can be found in only one place in the world

The critically endangered fish species can be found in only one cave in the middle of the Mojave Desert called Devil's Hole. In 2016, three men broke into the protected area to purposefully harm the fish.

Ancient sunken plates may influence mantle convection and surface motion

Research suggests sunken tectonic plates can collide, assemble, and break apart to form structures called large low-velocity provinces. LLVPs can significantly enrich rising magma plumes with elements commonly seen on Earth’s surface.

Learn how aquifers and wells provide the largest reserves of accessible freshwater on Earth

Roughly a third of Earth's freshwater is stored underground in aquifers—permeable and porous rock formations where water naturally flows from the Earth's surface and accumulates. About half of this groundwater is accessed through wells, a feat of engineering used for thousands of years.

Although earthquakes cause about 80% of tsunamis, almost all earthquakes lack sufficient energy to cause the sudden shift in the ocean floor needed to substantially displace enormous volumes of water.

Fracking provides access to fossil fuel reserves locked in underground rock

Using a pressurized fluid mixture that is over 90% water, cracks are created in shale about 2 miles deep to release trapped oil and natural gas. The process uses an average of 3 to 6 million gallons of water per well, which can strain local water supplies.

Cooling lava naturally creates hexagonal cracks to evenly relieve stress

When lava cools and turns into rock, it contracts and builds up tension, particularly when held in place by the surrounding landscape. Just as drying mud cracks, initial cracks in the rock are random, but quickly organize into a hexagonal pattern, which scientists consider the most space-efficient shape.

How water pressure affects the body

The extreme conditions of the deep sea include increasing amounts of pressure as explorers and organisms descend into its depths. The major danger for both fish and humans is the way pressure changes how body tissues absorb chemical molecules...

As of 2025, humans have only dug 0.2% the way to Earth's center

The Kola Superdeep Borehole revealed two billion-year-old fossils and underground water, but the immense temperature and pressure prevented further tunneling. Beyond those depths, scientists know of Earth's interior by analyzing how seismic waves move.

How scientists are using molecules found in acidophiles to develop new medical treatments

The Berkeley Pit, an open-pit copper mine in Butte, Montana, that ceased operations in 1982 and is now filled with highly acidic water, is home to various species of fungi and yeast. These extremophiles produce unique compounds that may have anti-inflammatory benefits and have already been used to create an antibiotic for staph infections.

Why do flash floods occur?

Flash flooding can be more dangerous than traditional floods, occurring within the span of hours and exhibiting rapid currents. Here's how atmospheric conditions and geography combine to make some locations ripe for the disaster.

Thunderquakes—seismic waves created when lightning strikes the ground—have enabled scientists to image underground environments near Earth's surface by detecting vibrations along subterranean fiber-optic cables.

In 2009, accidentally drilling into magma provided time capsules of volcanic glass

While drilling for geothermal energy in Iceland's Krafla Geothermal Field, magma encountered at a depth of 2,100 meters quickly formed glass upon making contact with drilling fluid. By trapping dissolved gases, volatile chemicals, and the physical characteristics of magma before cooling, the glass acts as a time capsule of ancient volcanic activity and magmatic conditions.

Mid-ocean ridges are underwater volcano systems where tectonic plates diverge

New ocean crust is formed at these ridges as magma rises from Earth’s mantle and fills the space between the spreading plates. The speed of divergence influences ridge shape, with slow spreads forming rugged valleys and fast spreading creating smooth, wide slopes.

Deep water corals—located throughout the world's ocean basins at depths beyond 200 meters (660 feet)—slowly build small coral gardens in the dark with the help of underwater worms.

Enter the Mayan underworld through this 3-mile cave

Discoveries in Belize's Actun Tunichil Muknal (ATM) cave suggest the cave was once a significant site for sacred Mayan ceremonies in antiquity. New research reveals how the Mayans conducted rituals to re-enact a specific creation myth, often staged in desperate times and aimed to invoke the gods for a "rebirth" amid drought and turmoil. Read more on the enigmatic research here.

While constructing the tunnel connecting the UK and France, satellite positioning systems were supplemented by paleontologists on either side of the tunnel, who analyzed fossils to ensure excavation was at the correct depth.

Some scientists hypothesize that stressed rocks can discharge built-up static electricity in the form of lightning—a phenomenon known as fracto-luminescence, or earthquake lights.

Modern landfills use layered liners, leachate systems, and gas monitors to safely contain waste

Today, landfill engineering is far more complex than a hole in the ground, which was largely the system cities used less than a century ago. This video explains how it actually works.

If the temperature of water continuously decreases but it is not given room to expand, it will eventually contract and form exotic forms of ice that sink in liquid water.

Whale falls—dead whales that have fallen to the ocean's floor—can provide enough food to spawn a local ecosystem of deep-sea organisms that lasts for decades.

Some marine life can survive the extreme pressure of the deep ocean because of specialized molecules that strengthen proteins, enzymes, and cellular membranes.

Disposal wells for fracking wastewater have been linked to spikes in seismic activity

A study of all such underground wells in the central and eastern US found that they were 1.5 times more likely to be associated with earthquakes than oil recovery wells. The link between fluid injection and earthquakes was strongest at disposal wells where fluid was injected quickly.

Large igneous provinces are regions of massive ancient volcanic activity

Linked to some mass extinction events on Earth, LIPs contain significant amounts of igneous rock formed by the release of lava and gases over millions of years. India's Deccan Traps and the Siberian Traps are prominent examples of LIPs, whose climate-related impacts can serve as models for analyzing modern climate change.

The moon is slowly contracting as its interior cools, creating moonquakes and lobate scarps—cliffs that are steep on one side and gently sloping on the other—as the moon's surface buckles.

While major oil spills result from accidental pipeline ruptures or damage to transportation vessels or rigs, as much as half the oil that reaches coastlines has naturally leaked from the seafloor.