Geological formations: canyons, caves, rock formations

Antelope Canyon is a slot canyon formed in Navajo Sandstone through erosion by flash floods over thousands of years. This geological formation consists of two main sections located about three-quarters of a mile (1.2 km) apart, each displaying distinct geological features. The undulating walls show layering from different periods of sedimentation, while daylight filtering through openings reveals shifting tones across the sandstone surfaces. The canyon is located on Navajo Nation land and requires access through authorized guides who manage entry to the sections.

This sea cave on the uninhabited Hebridean island of Staffa demonstrates the work of volcanic processes through its walls of hexagonal basalt columns formed about 60 million years ago by slowly cooling lava. The geometric arrangement gives Fingal's Cave an architectural appearance that has drawn geologists and visitors since the 18th century. The entrance faces the sea and floods partially at high tide, and the natural acoustics inspired Felix Mendelssohn to compose his Hebrides Overture following his visit in 1829.

The Giant's Causeway consists of around 40,000 interlocking basalt columns formed by volcanic activity approximately 60 million years ago along Northern Ireland's north coast. This geological site displays mostly hexagonal columns that create a natural pavement extending from the cliff face into the sea, documenting the forces that shaped the region during the Paleogene period when molten basalt reached the surface and cooled into these distinctive formations.

This granite formation rises as a 50-foot high rock face in Western Australia and demonstrates the erosive work of wind and water over 2.7 billion years. Wave Rock illustrates how chemical weathering and natural drainage processes shaped the granite into a curved form resembling a breaking ocean wave. Vertical stripes in gray, red and ochre formed through mineral deposits that flowed down the rock face. The formation extends 360 feet (110 meters) in length and belongs among the geological phenomena in this collection that document natural processes across deep time.

These geological formations consist of more than 1,268 cone-shaped hills spread across an area of approximately 19 square miles (50 square kilometers). The Chocolate Hills formed through the uplift of coral limestone sediments and subsequent erosion by rain and groundwater over several million years. During the dry season, the grass vegetation turns brown and gives the hills their characteristic appearance.

These travertine terraces formed over thousands of years as mineral-rich thermal water flowed down the hillside, depositing white calcium carbonate layers. Pamukkale, meaning "cotton castle," consists of a series of stepped pools that extend along the edge of the Taurus Mountains for 1.7 miles (2.7 kilometers). The water, which emerges from underground springs at temperatures around 95°F (35°C), has created the distinctive travertine formations that function today as both a geological monument and an active thermal bathing site.

The Apostles are a formation of limestone stacks off the coast of Port Campbell National Park in Victoria. These formations developed through millions of years of erosion, as waves and wind wore away the sandstone cliffs of the coastline and left individual stacks in the ocean. The formations reach heights of up to 145 feet (45 meters) and continue to be shaped by the ongoing action of the Southern Ocean. The Apostles illustrate the geological processes of coastal erosion and demonstrate the vulnerability of sedimentary rock to maritime forces.

Yehliu Geopark occupies a narrow promontory on Taiwan's northern coast, where wave action over thousands of years has carved distinct erosion patterns into the sandstone bedrock. The formations include honeycomb weathering, mushroom rocks with narrow stems and wider caps, and candle-shaped pillars created by differential erosion of harder and softer rock layers. This coastal site demonstrates the effects of wind, waves and salt spray on sedimentary formations and remains one of Taiwan's most studied examples of marine erosion.

This desert in the Western Sahara forms a landscape of white limestone formations shaped by wind and sand abrasion over thousands of years. The White Desert extends across roughly 115 square miles (300 square kilometers) north of the Farafra Oasis and presents mushroom-shaped, conical and abstract structures of chalk deposits that contrast with the surrounding sandy ground. This geological formation ranks among the accessible examples of aeolian erosion processes in arid climates.

This wetland in Liaoning province extends across the Liaohe River delta and provides habitat for numerous bird species. The area derives its distinct color from Suaeda salsa, a salt-tolerant plant that turns red in autumn. The wetland covers approximately 77 square miles (200 square kilometers) and consists of reed fields, salt marshes and tidal flats. Visitors can walk on wooden boardwalks through various zones, while the area serves as a stopover for migratory birds on the East Asian flyway.

This massive limestone formation rises 289 feet (88 meters) from the Gulf of Saint Lawrence at the tip of the Gaspé Peninsula, demonstrating the erosive power of seawater through its distinctive natural arch. Percé Rock consists of 375-million-year-old Devonian rock and serves as an important seabird sanctuary with thousands of nesting gannets. Visitors can walk around the formation at low tide and observe the layered sedimentary strata and fossil deposits that document ancient marine environments.

These rock formations in the Cappadocia region formed through volcanic activity and subsequent erosion over millions of years. The Fairy Chimneys consist of softer tuff topped by harder basalt caps that protected the underlying stone from weathering. In Monks Valley and other parts of the region, these cone-shaped structures reach heights of up to 130 feet (40 meters). Early Christian communities carved out many of these formations to create living spaces and churches that remain visible today.

Jeju Volcanic Island formed through volcanic activity that shaped a landscape of lava rock, craters and basaltic columns over millions of years. The island demonstrates geological processes created by magma flows and erosion. Waterfalls cascade over dark basalt rock formations, while solidified lava streams define coastal areas. The site documents volcanic formation history and provides access to various geological structures characteristic of this collection.

The Trona Pinnacles consist of more than 500 geologic towers rising up to 140 feet (43 meters) above the floor of the Mojave Desert in California. These formations developed between 10,000 and 100,000 years ago when the area was part of Searles Lake. Soluble minerals including sodium carbonate formed through chemical processes in the alkaline water and solidified into the structures visible today. The site has served as a filming location for various motion pictures and sits on public land managed by the Bureau of Land Management.

Los Glaciares forms the third largest freshwater reserve on Earth with its ice cap feeding 47 major glaciers. This geological complex in the Patagonian Andes demonstrates ongoing glacial processes in a region where ice masses continue to advance and calve. The glacier landscape encompasses various glacier types, from hanging glaciers to valley glaciers that have carved fjords and lakes. Scientists monitor these ice formations regularly to document the effects of climate change on Patagonian glaciers.

The Tsingy de Bemaraha demonstrates the result of erosion processes on limestone formations over thousands of years and belongs to the most distinctive geological structures in this collection. The area covers 72,000 hectares and has been designated a UNESCO World Heritage Site. The needle-shaped rock spires reach heights up to 150 feet (46 meters) and are separated by narrow gorges. Researchers use this karst landscape to study erosion mechanisms in tropical climates. Numerous endemic plant and animal species have adapted to the conditions between the limestone needles.

The Dasht-e Lut extends across much of southeastern Iran and ranks among the hottest and driest regions on Earth. This salt desert displays landforms shaped by geological processes, including extensive dune fields and rock formations sculpted by wind erosion over millions of years. Summer temperatures reach extreme levels, with ground measurements exceeding 160 degrees Fahrenheit (70 degrees Celsius) documented in the area. The terrain encompasses distinct morphological zones featuring salt crusts, undulating sand structures and eroded rock masses that provide scientific insights into arid climate conditions and surface processes.

This karst formation in Shilin Yi Autonomous County in China's Yunnan Province consists of limestone pillars reaching several hundred feet in height, formed through erosion and calcium carbonate dissolution over approximately 270 million years. The Stone Forest covers roughly 154 square miles (400 square kilometers) and features gray stone columns that resemble trees. The formation began as a seafloor during the Permian period, was then uplifted through tectonic activity and shaped into its current form through chemical weathering. Visitors can walk on marked trails between the rock formations and explore different sections, including the Major Stone Forest with the tallest pillars and the Minor Stone Forest with denser structures. The geological site has been part of the UNESCO World Heritage South China Karst since 2007.

This wooded park in Hunan Province contains over 3,000 quartzite sandstone pillars formed through erosion over 380 million years. The formations of Zhangjiajie National Forest Park reach heights up to 660 feet (200 meters) and are connected by limestone caves, gorges and natural bridges. The sandstone columns are covered with subtropical vegetation and served as inspiration for landscapes in films. The park spans 185 square miles (480 square kilometers) and is accessed by cable cars, a glass walkway and hiking trails.

This freestanding sandstone pillar rises 30 meters (100 feet) high on the Black Sea shore south of Gelendzhik. Sail Rock was separated from the mainland through erosion and displays a distinct rectangular opening near its base created by wave action. The formation demonstrates geological processes where softer rock erodes faster than surrounding harder layers, leaving an isolated structure.

This saline endorheic alkali lake in south-central British Columbia leaves behind distinctive mineral circles as water evaporates during summer months. Spotted Lake contains high concentrations of magnesium sulfate, calcium sulfate and sodium sulfate, along with traces of silver and titanium. The different colored spots form as minerals of varying composition concentrate in separate pools. The site sits on Okanagan Nation territory and holds cultural and therapeutic significance for the indigenous population, who have used its waters for centuries.

This circular geological structure spans about 25 miles (40 kilometers) in diameter across the Sahara and displays concentric rings of different rock layers. The Eye of the Sahara formed through erosional processes that exposed older rock formations and created the characteristic ring pattern. The formation consists of different sedimentary and igneous rocks shaped by millions of years of geological activity.

This sea cave on Capri is known for the intense blue luminescence created when sunlight passes through an underwater opening and illuminates the interior. The Blue Grotto has attracted visitors since the 19th century who come to experience the glowing waters. The cave extends roughly 200 feet (60 meters) into the cliff face and reaches 50 feet (15 meters) in height, with access limited to a narrow entrance from the sea.

This table-top mountain rises to 9,219 feet (2,810 meters) at the border of Venezuela, Brazil, and Guyana, ranking among South America's oldest geological formations. Mount Roraima forms an isolated ecosystem with its own microclimate, sheltering endemic plant and animal species that have evolved over millions of years on the plateau. The vertical sandstone walls, carved by erosion over two billion years, demonstrate long-term geological processes in this region.

This hot spring in Yellowstone National Park produces concentric rings of color through thermophilic bacteria that inhabit different temperature zones. The Grand Prismatic Spring measures approximately 370 feet (113 meters) across and reaches temperatures up to 189 degrees Fahrenheit (87 degrees Celsius) at its center. The intense blues, greens, yellows and oranges of the water result from microbial mats producing different pigments, while the deep blue at the center comes from light absorption and scattering in the clear, mineral-rich water. This geothermal formation is the third largest hot spring in the world and demonstrates the volcanic activity beneath the Yellowstone caldera.

This geological depression sits more than 300 feet (100 meters) below sea level and ranks among the hottest inhabited places on Earth. The Danakil Depression displays sulfur springs in shades of yellow and green, extensive salt flats and active lava lakes formed by volcanic activity in the East African Rift. Temperatures regularly reach 120 degrees Fahrenheit (50 degrees Celsius).

This saline lake in eastern California contains prominent tufa towers rising as calcium carbonate formations above the water surface. The porous structures formed through chemical reactions between saline lake water and calcium-rich freshwater springs at the bottom. Mono Lake spans approximately 70 square miles (180 square kilometers) and represents one of North America's oldest continuous bodies of water, dating back at least 760,000 years. The high salinity supports a specialized community of species including brine shrimp and alkali flies that provide food for migratory birds.

These rounded stone spheres lie scattered on Koekohe Beach along the Otago coast and measure up to 7 feet (2 m) in diameter. The Moeraki Boulders formed over several million years through mineral deposits accumulating around a core in seafloor mud that later solidified into rock. Erosion exposed the concretions, and some now display cracks or split structures revealing their crystalline interiors.

Salar de Uyuni covers 4,086 square miles (10,582 square kilometers) in the Bolivian Altiplano and forms the largest salt flat on Earth. After rainfall, the surface creates a mirror effect that reflects the sky and surrounding landscape. The formation resulted from the evaporation of prehistoric lakes several thousand years ago and consists of a salt crust several meters thick.

This bay in northern Vietnam unfolds across 1,553 square miles (4,000 square kilometers) of the Gulf of Tonkin, where over 1,600 limestone islands and islets rise from the water. The karst formations developed through 500 million years of geological activity, with sea levels exposing the weathered limestone pillars. Ha Long Bay demonstrates the advanced stage of marine karst evolution in tropical climates. Most islands remain uninhabited and feature steep flanks rising 50 to 100 feet (15 to 30 meters), while many host hollow chambers and grottoes shaped by wave erosion. The area supports several floating fishing villages.

This rock formation extends horizontally from Mount Skjeggedal and overlooks Lake Ringedalsvatnet some 2,300 feet (700 meters) below. Trolltunga formed approximately 10,000 years ago as glaciers eroded the surrounding rock layer and shaped this protruding spur of bedrock. The formation sits in a region that was covered by thick inland ice during the last glacial period.

This cave lies 1,000 feet (300 meters) beneath the surface at the Naica Mine and contains some of the largest natural crystal formations on Earth. The Cave of Crystals holds selenite crystals that reach lengths of up to 36 feet (11 meters) and weigh several tons. Extreme heat and humidity inside the cave, which reaches temperatures around 122°F (50°C), limits unprotected visits to just minutes. These crystals grew over approximately 500,000 years under constant geological conditions.