This page lists 60 geological features that start with C, from “Caldera” to “Crater of Diamonds.” The list covers landforms, rock types, minerals, and underground and underwater structures found around the world. Whether you study earth science, plan a trip, or are just curious, you can use it to learn names, spot places worth visiting, and understand how the planet is shaped.
Geological features are the natural formations, rocks, and structures that make up Earth’s surface and interior. Some are famous far beyond science: the cenotes of the Yucatán Peninsula were sacred to the ancient Maya, who saw them as gateways to the underworld.
Below you’ll find the table with the feature, region, characteristics, and description of each entry.
Feature: The common name of each geological feature, listed in alphabetical order so you can quickly find the one you want.
Region: Where the feature is found, including well-known examples, so you can see whether it is local to you or worldwide.
Characteristics: A short summary of what makes the feature stand out, which helps you compare similar items at a glance.
Description: A plain-language explanation of how the feature forms and what it looks like, giving you the key facts without technical jargon.
Geological features
| Feature | Region | Characteristics |
|---|---|---|
| Caldera | Worldwide (e.g. Yellowstone, Crater Lake) | Large volcanic depression |
| Canyon | Worldwide (e.g. Grand Canyon, USA) | Deep, steep-sided valley |
| Cape | Coastal regions worldwide | Headland extending into the sea |
| Cave | Worldwide | Natural underground chamber |
| Cavern | Karst regions worldwide | Large cave chamber |
| Cenote | Yucatán Peninsula, Mexico | Water-filled sinkhole |
| Channel | Worldwide | Passage carved by flowing water |
| Chimney Rock | Western USA, Southwest Asia | Tall isolated rock column |
| Cinder Cone | Volcanic regions worldwide | Steep, small volcano |
| Cirque | Mountain regions worldwide | Bowl-shaped glacial hollow |
| Clast | Worldwide | Broken rock fragment |
| Clay | Worldwide | Fine-grained soil material |
| Claystone | Worldwide | Fine sedimentary rock |
| Cleavage | Worldwide | Rock or mineral splitting pattern |
| Cliff | Coastal and mountain regions worldwide | Steep rock face |
| Coal Seam | Worldwide (e.g. Appalachia, Powder River Basin) | Layer of fossilized plant material |
| Coast | Worldwide | Land meeting the sea |
| Col | Mountain ranges worldwide | Low point between two peaks |
| Columnar Jointing | Giant’s Causeway (Northern Ireland), Devils Tower (USA) | Hexagonal rock columns |
| Concretion | Worldwide (e.g. Moeraki Boulders, New Zealand) | Rounded mineral lumps in sediment |
| Conglomerate | Worldwide | Sedimentary rock with rounded pebbles |
| Continent | Worldwide | Massive landmass |
| Continental Shelf | Edges of continents worldwide | Shallow submerged land |
| Continental Slope | Edges of continents worldwide | Steep seafloor descent |
| Coral Reef | Tropical oceans (e.g. Great Barrier Reef, Australia) | Living limestone structure |
| Core | Earth’s center | Hot, dense inner layer |
| Corrie | Scotland, Ireland, Wales | Glacial bowl-shaped valley |
| Crater | Volcanic and impact sites worldwide | Bowl-shaped depression |
| Crater Lake | Oregon, USA | Deep volcanic lake |
| Craton | Ancient continental interiors (e.g. Canadian Shield) | Old stable crust |
| Crevasse | Glaciers and ice sheets | Deep crack in ice |
| Crust | Worldwide | Earth’s outer layer |
| Crystal | Worldwide | Ordered mineral structure |
| Crystal Cave | Naica, Mexico | Giant selenite crystals |
| Cuesta | Dry and sedimentary regions worldwide | Gently sloping ridge with one steep side |
| Cut Bank | River valleys worldwide | Eroded outer river bend |
| Cutoff | River floodplains worldwide | Abandoned river loop |
| Cuspate Foreland | Coastlines worldwide (e.g. Cape Canaveral, USA) | Triangular coastal point |
| Cwm | Wales, UK | Glacial mountain hollow |
| Cataract | Rivers worldwide (e.g. Nile cataracts) | Large waterfall or rapids |
| Cascade | Rivers and mountains worldwide | Stepped waterfall |
| Cave Pearl | Limestone caves worldwide | Small round cave deposit |
| Cave Pillar | Limestone caves worldwide | Column of mineral deposits |
| Calcite | Worldwide | Common carbonate mineral |
| Chalk | England, France, Kansas (USA) | Soft white limestone |
| Chert | Worldwide | Hard, fine-grained silica rock |
| Chasm | Worldwide | Very deep gap in the earth |
| Chimney (Hydrothermal Vent) | Deep ocean ridges | Mineral tower on seafloor |
| Cirque Glacier | Mountain regions worldwide | Small glacier in a hollow |
| Coastal Plain | Gulf Coast USA, Brazil, India | Flat land near the sea |
| Coral Atoll | Pacific and Indian Oceans (e.g. Maldives) | Ring-shaped reef island |
| Cordillera | Americas (e.g. Andes, Rocky Mountains) | Long mountain chain |
| Crag | Scotland, Northern England | Steep rugged rock face |
| Creek Bed | Worldwide | Channel of a small stream |
| Cryptovolcano | Worldwide (e.g. Steinheim Basin, Germany) | Circular volcanic-like structure |
| Cuvette | Africa and sedimentary basins | Wide basin-shaped depression |
| Cave of Crystals | Chihuahua, Mexico | Giant gypsum crystals |
| Cliff Dwelling Alcove | Southwestern USA (e.g. Mesa Verde) | Rock shelter in canyon walls |
| Columbia River Basalt | Pacific Northwest, USA | Massive lava flow plateau |
| Crater of Diamonds | Arkansas, USA | Diamond-bearing volcanic pipe |
Descriptions
Caldera
A huge bowl-shaped depression formed when a volcano empties its magma chamber and the ground collapses. Calderas can be many miles wide and sometimes fill with water.
Canyon
A deep valley with steep walls, usually carved over millions of years by a river cutting through rock. Canyons often reveal layers of Earth’s geologic history.
Cape
A large point of land that juts out into a sea or ocean. Capes are usually formed from harder rock that resists erosion better than the coastline around them.
Cave
A natural hollow space in the ground big enough for a person to enter. Caves form through dissolving rock, lava flows, wave action, or ice melting.
Cavern
A very large cave or a spacious chamber within a cave system. Caverns are often found in limestone, where water has slowly dissolved the rock.
Cenote
A natural sinkhole that exposes groundwater, formed when limestone bedrock collapses. Cenotes were sacred to the ancient Maya and are popular for swimming and diving today.
Channel
A narrow passage or trench where water flows, either on land or on the seafloor. Channels can be cut by rivers, glaciers, or ocean currents.
Chimney Rock
A tall, narrow rock pillar left standing after surrounding softer rock wears away. Chimney rocks often stand alone on plains or hillsides.
Cinder Cone
A small, steep-sided volcano built from fragments of lava thrown out of a single vent. Cinder cones usually form quickly and are rarely more than a few hundred feet tall.
Cirque
An amphitheater-shaped valley at the head of a glacier, carved by ice. Cirques often hold small lakes called tarns once the glacier melts.
Clast
A fragment of rock or mineral that has been broken off from a larger piece. Clasts range from tiny grains to giant boulders and make up sedimentary rocks like conglomerate.
Clay
A very fine-grained natural material made of tiny mineral particles. Clay becomes sticky when wet and hardens when dried or fired, making it useful for pottery and bricks.
Claystone
A sedimentary rock made mostly of hardened clay particles. It forms when layers of fine mud are compacted over time.
Cleavage
The tendency of a mineral or rock to split along flat, even surfaces. Mica splits into thin sheets because of its strong cleavage.
Cliff
A tall, steep rock face, often found along coasts or the edges of plateaus. Cliffs form through erosion, faulting, or wave action.
Coal Seam
A layer of coal sandwiched between other rock layers. Seams form from ancient swamp vegetation buried and compressed over millions of years.
Coast
The area where land meets the ocean. Coasts are shaped by waves, tides, currents, and the type of rock or sediment present.
Col
The lowest point on a ridge between two higher summits. Cols often serve as natural mountain passes.
Columnar Jointing
A pattern of tall, many-sided rock columns formed when lava cools and cracks as it contracts. It creates striking natural stone pillars.
Concretion
A hard, often rounded mass formed when minerals gather around a nucleus in sedimentary rock. Some concretions look like perfectly shaped spheres.
Conglomerate
A sedimentary rock made of rounded pebbles and gravel cemented together. It often forms in ancient riverbeds or beaches.
Continent
One of Earth’s seven large landmasses. Continents sit on tectonic plates that slowly shift over geologic time.
Continental Shelf
The gently sloping seafloor extending out from a continent’s coast before dropping steeply. Shelves are rich in marine life and resources.
Continental Slope
The steeper slope that drops from the edge of a continental shelf toward the deep ocean floor. It marks the true edge of a continent’s crust.
Coral Reef
An underwater structure built from the calcium carbonate skeletons of coral animals. Reefs take thousands of years to grow and shelter huge numbers of sea creatures.
Core
Earth’s innermost region, made mostly of iron and nickel. It has a liquid outer layer and a solid inner ball.
Corrie
A regional name for a cirque, an armchair-shaped hollow carved by glacial ice. The term is used mainly in Scotland and Ireland.
Crater
A round, bowl-shaped hole formed by a volcanic eruption or a meteorite impact. Craters can be small pits or many miles wide.
Crater Lake
A lake filling the caldera of a collapsed volcano, Mount Mazama. It is the deepest lake in the United States and known for its intense blue color.
Craton
A very old, stable part of a continent’s crust that has survived for billions of years. Cratons form the cores of most continents.
Crevasse
A deep, open crack in a glacier caused by the ice moving and stretching. Crevasses can be hidden by snow and are dangerous for climbers.
Crust
The thin, rocky outer shell of Earth. It is divided into continental and oceanic crust and sits on top of the mantle.
Crystal
A solid whose atoms are arranged in a repeating pattern, giving it flat faces and sharp angles. Quartz and salt are common examples.
Crystal Cave
A cave in Mexico containing some of the largest natural crystals ever found, some over 30 feet long. The cave is extremely hot and humid.
Cuesta
A ridge with a gentle slope on one side and a steep cliff on the other. Cuestas form where tilted layers of hard and soft rock erode at different rates.
Cut Bank
A steep bank on the outside of a river bend, where fast-flowing water erodes the land. It is the opposite of a gentle point bar.
Cutoff
A shortcut that forms when a river breaks through a narrow neck of land at a meander. The abandoned loop often becomes an oxbow lake.
Cuspate Foreland
A pointed, triangular piece of land formed by sediment deposited by waves and currents. It extends from the coastline into the sea.
Cwm
The Welsh word for a cirque, a bowl-shaped valley carved out by glacial ice. It is common in the mountains of Snowdonia.
Cataract
A large, powerful waterfall or a series of strong rapids on a river. The Nile has six famous cataracts in Egypt and Sudan.
Cascade
A small waterfall or series of waterfalls that flow over rock steps. Cascades often form where rivers cross layers of different hardness.
Cave Pearl
A small, polished, rounded stone that forms in cave pools as minerals build up around a grain of sand. Water dripping on them keeps them rolling and smooth.
Cave Pillar
A column that forms when a stalactite and stalagmite grow until they meet. These pillars can take thousands of years to form.
Calcite
A common mineral made of calcium carbonate, found in limestone, marble, and cave formations. It often forms clear or white crystals.
Chalk
A soft, white, fine-grained limestone made from the shells of tiny marine organisms. The White Cliffs of Dover are made of chalk.
Chert
A hard, dense sedimentary rock made of microscopic quartz crystals. Early humans used chert to make sharp tools.
Chasm
A deep, wide crack or gap in the ground or rock. Chasms can be formed by earthquakes, erosion, or tectonic movement.
Chimney (Hydrothermal Vent)
A tall tower of minerals formed on the seafloor where hot, mineral-rich water gushes out. Some chimneys, called black smokers, release dark, hot fluid.
Cirque Glacier
A small glacier that sits inside a bowl-shaped hollow high on a mountain. It slowly deepens the hollow by freezing and plucking rock away.
Coastal Plain
A broad, low-lying area of flat land that borders the ocean. It often forms from sediments deposited as the sea retreated.
Coral Atoll
A ring-shaped coral reef or chain of islands surrounding a central lagoon. Atolls often form on top of sunken volcanoes.
Cordillera
A large system of parallel mountain ranges, especially in western North and South America. The word comes from Spanish for “little rope.”
Crag
A steep, rugged mass of rock that sticks out from the surrounding land. Crags are popular spots for rock climbing.
Creek Bed
The bottom of a small stream, carved by flowing water. Creek beds can be dry for part of the year in arid areas.
Cryptovolcano
A circular geological structure that looks like it was formed by a volcanic explosion but has no clear volcanic origin. Many are now linked to meteorite impacts.
Cuvette
A broad, shallow, basin-like depression in the land, often in tropical Africa. The term is used for large, bowl-shaped sedimentary areas.
Cave of Crystals
A famous cavern lined with enormous beams of selenite crystals. It sits above a magma chamber that heated the water that grew them.
Cliff Dwelling Alcove
A natural hollow in a cliff face, formed by erosion of softer rock layers. Ancestral Puebloans built homes inside alcoves like these.
Columbia River Basalt
A huge series of ancient lava flows that covers parts of Washington, Oregon, and Idaho. The flows erupted about 16 million years ago.
Crater of Diamonds
An eroded volcanic pipe in Arkansas where visitors can search for real diamonds. It is one of the few diamond sites open to the public.