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

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.

Sinkholes form when underground cavities cause the surface above to collapse

These openings are typically carved by acidic water, which often forms in limestone-rich areas. However, leaking pipes, groundwater removal and extreme weather or geological activity increases the frequency of sinkhole appearances.

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.

Distinguishing the three types of mineral deposits collected via deep-sea mining

The greatest interest is in polymetallic nodules—structures formed from metals in seawater collecting around a core of shell, bone, or rock. Cobalt-rich ferromanganese crusts cover underwater mountain ranges and form over millions of years of metal deposition. Polymetallic sulfide deposits accumulate when seawater seeps into volcanic rocks.

How did ancient cave painters manage to see what they were doing?

As ancient artists made their way deep into caves and created massive works of art that continue to inspire awe today, they would've required light sources to see what they were doing. This gallery details some of the light sources that cave artists...

The 15 most beautiful caves in the United States

The United States is home to more than 45,000 caves, including many with National Parks designation, like Wind Cave (in South Dakota) and Carlsbad Caverns (in New Mexico). This list of the 15 best isn't just for spelunkers—all of these sites are available for more typical tourists, so long as they have a good pair of shoes.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

The importance of coral reefs since their first appearance hundreds of millions of years ago

Formed from calcium carbonate skeletons deposited by hard corals, some estimates suggest these reefs provide habitats for over a million marine species. Spanning massive areas, coral reefs also serve as buffers against extreme weather, such as tropical storms.

Learn why water can take millions of years to be recycled via the hydrologic cycle

While a single drop of water spends an average of nine days in the atmosphere before precipitating back to Earth, it can spend thousands of years in the ocean before evaporating, and hundreds of thousands of years deep in rock layers before being released as steam in volcanic eruptions. Some water molecules have been trapped in Antarctic ice sheets for millions of years since they last moved through the water cycle.

Learn about endoliths, the polyextremophiles that thrive inside rocks

These organisms include species that live in Antarctica, where they perform photosynthesis using light and water that makes it through pores in sandstone. Others residing in Earth's crust can survive temperatures reaching 60 degrees Celsius (140 degrees Fahrenheit) while generating energy through chemical reactions involving nutrients and gases trapped in rocks.

Extraterrestrial volcanoes spew material present during their formation

Unlike Earth's volcanoes that release lava, cryovolcanoes on distant moons erupt cold jets of water, ammonia, and other light gases present during the formation of their host planet. The movement of internal heat produced during formation is thought to drive icy plume movement.

Mammals thrived under the feet of dinosaurs

An explosion of fossil finds reveals that ancient mammals evolved a wide variety of adaptations allowing them to exploit the skies, rivers and underground lairs.

The surprising world of coal seam fires

Hundreds of coal seam fires are actively smoldering around the world at any given time, including some that have stayed lit for centuries. These fires have occurred naturally for millions of years, lit atop deposits of coal in the earth. Dive into...

Airborne microplastics may influence cloud formation and climate

Microplastics are increasingly found in the atmosphere and may affect the climate by reflecting or absorbing sunlight based on their pigmentation. Like mineral dust, they may become cloud seeders and alter regional precipitation patterns as they become more abundant.

Layers of minerals revealed by erosion give Vinicunca its distinct colorations

Located in Peru's Andean mountains, Rainbow Mountain is known for its vibrant colors, which result from layers of minerals such as clay, sandstone, argillite, and limonite exposed over millions of years by rain, snowfall, and strong winds.

Distinguishing club soda, seltzer, and sparkling water

The three forms of drinking water are similar, but their differences lie mostly in the presence and proportion of minerals and carbonation. Read this quick explainer on the major differences.

The ratio of stable carbon isotopes in climate proxies provides climate variable data

Measures of the abundance of carbon-13 and carbon-12 can vary in a sample due to environmental and climatic factors. Plants more readily assimilate carbon-12 during photosynthesis, allowing the ratio to serve as a proxy for past conditions that favored plant life.

Watch tardigrade samples under an optical microscope

Tardigrade samples can be collected by gathering moss and submerging it in tap water for 24 hours. The moss should then be cut and drained with a mesh sieve, and the water should be collected. Samples are observable in the water between 10x and 40x magnifications.

Humans have used geothermal resources for thousands of years

In North America, Indigenous peoples viewed hot springs as sacred places and used them for medicinal purposes, cooking, and surviving cold weather. The ancient Greeks and Romans also viewed them as sacred, partaking in hot mineral baths to relieve ailments and using them for space heating.

Gastroliths, or ‘stomach stones,’ help animals digest plants in their stomachs

Most often used by birds and reptiles, gastroliths help break down the cellulose of plant cells, which can resist decomposition from stomach acid alone. Over time, gastroliths become smooth and are regurgitated before being replaced by larger stones.

Shape memory alloys 'remember' their previous form and restore themselves if deformed

Nitinol, one such alloy, can bend back into its trained shape if exposed to heat because of a solid-to-solid phase transformation. Some showerheads already use nitinol to regulate hot water and prevent unintentional burns.

A basement of mechanical systems—collectively called the technosphere—supports B2

Twenty-six underground air handlers heat, cool, filter and manage the humidity of the air across the biomes of Biosphere 2. The above-ground Energy Center complex provides continuous power to these and other systems, including heating and cooling water for laboratory experiments and personal use.

Fungi make people sick when they invade and survive in otherwise healthy human tissue

We breathe in airborne spores frequently, but they often don't make us sick. This video details how certain concerning fungal changes can occur and discusses the role of mycologists—scientists who study fungi—in helping to improve human health.

Surfer's ear, from repeated cold water exposure, leads to new bony protrusions in the ear

Frequent exposure to icy cold water, typical in surfing, can cause tiny bony growths to develop in the ear canal, informally called surfer's ear. While the exact cause for these growths is unknown, it may be the body's protective response to shield the ear drum from the cold. These protrusions can heighten the risk of swimmer's ear, lead to wax buildup, and result in hearing loss.

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.

Stonehenge produces concert-hall-like acoustics

Acoustics researcher Trevor Cox discovered that Stonehenge acts like a concert hall, reflecting and amplifying sound. This video shows Cox demonstrating the effect using a scale model inside a soundproof studio.

Massive blooms of microscopic plankton called dinoflagellates produce the neon blue light seen in glowing tides.

See photos of Meteora, a mountainous site in central Greece, home to 14th-century monasteries perched atop soaring outcroppings.

A 101 on the science and history of meteor showers

Bits of rock, ice, and dust flying through space called meteors burn up in a spectacular display when they hit our atmosphere 60 miles up at an average of 30,000 mph. Some of these are isolated objects, but others are recurring phenomena caused by...

Watch how deep-sea mining equipment collects and processes polymetallic nodules—metal-rich, potato-shaped rocks—from the ocean floor and creates environmentally damaging plumes of sediments.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

Corals are themselves not coral reefs—the term refers to the tiny marine invertebrates that build the rigid reef.

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Shooting stars, or meteors, are fragments of asteroids and comets that burn up as they enter Earth's atmosphere, creating streaks in the sky called meteor showers.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

Graffiti dates back to at least ancient Pompeii, where citizens scrawled messages to one another on public walls

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Scientists have struggled to pin down Ebola's natural reservoir species for decades, but the available evidence suggests that it's very likely fruit and insect-eating bats found in Africa.

The first horror movie is believed to be George Méliès' 1986 short 'The Haunted Castle,' which pioneered the use of special effects

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

See how Budweiser's famous Clydesdales spend their days at Warm Springs Ranch, where roughly 70 to 80 of the beer brand's giant horses can be found at any given time.