Stalactites hang from the ceiling of caves, while stalagmites grow upward from cave floors.
What is the difference between a stalagmite and a stalactite?
There’s a time and place for everything in English grammar, and today our focus is on two geology terms we’re all bound to confuse: stalagmite and stalactite.
The nouns “stalagmite” and “stalactite” are not commonly found outside of scientific articles or travel blogs, and that’s because they tend to reference a type of common speleothems (i.e., cave formations made of secondary mineral deposits).
The key difference between the two formations is that stalactites hang down from cave ceilings with a pointed tip, while stalagmites have more rounded tips that grow up from the floor of caves.
Speleothems, stalagmites, and stalactites
Traditional definitions of the nouns “stalagmite” and “stalactite” reference a common type of speleothem: secondary mineral deposits formed in caves by pooled, sweeping, flowing, or dripping groundwater.
Flowstone, helictites, anthodites, and gypsum flowers are all “types of speleothem” (among many others), but stalagmites and stalactites are perhaps the most exciting speleothems of them all.
What are stalactites?
Stalactites (named from the Greek word stalagma for ‘a drop’ or ‘a drip’) are hollow, icicle-shaped formations that hang from the roof of caves. The sharp, pointy formations consist of precipitated minerals accumulated from the steadily dripping water.
What are stalagmites?
Stalagmites (named from Greek stalaktos for ‘dripping’ or ‘oozing out in drops’) are the corresponding formation of stalactites that rise from cave floors and point upward. The tips of stalagmites are more convex or flattened than stalactites, often taking a candlestick appearance.
Warning: Not all speleothem are stalagmites or stalactites and vice versa
A crucial part of using the words “stalagmite” and “stalactite” is to understand when these structures reference a speleothem or not. Speleothem structures are made from secondary mineral deposits in caves, but not all stalagmites and stalactites are created in caves or from secondary deposits of minerals.
Outside of caves, a “stalagmite” can be any hollow, icicle-shaped structure that hangs suspended, accumulating deposited minerals from some form of dripping liquid. Likewise, a “stalactite” can form in various environments where there’s a continuous dripping of mineral-rich water or a similar deposit of other material.
Speleothems are often made from calcite, aragonite, and gypsum in limestone caves (the chief form of calcium carbonate rock) and can include deposited minerals like opla, chalcedony, and limonite.
Non-speleothem formations can occur on the ceiling of hot springs, basements, mines, within lava tubes, or underneath bridges from a variety of minerals and materials, including concrete, dirt, sand, mud, sinter, peat, pitch, and lava.
Common types of non-speleothem stalactites and stalagmites include:
- Concrete stalactites/stalagmites: The accumulation of “calthemite,” or leaking minerals such as calcium and magnesium from concrete.
- Lava stalactites/stalagmites: Cooled molten lava within lava tubes.
- Ice stalactites/stalagmites: “Icicles” created from sweeping water in freezing weather.
How do stalactites and stalagmites form?
Stalactite and stalagmite formation occurs in caves from a process called chemical weathering, which is essentially any chemical interaction that erodes or breaks down rock minerals with water.
To create stalactites and stalagmites, cave surfaces must provide a water-soluble mineral or “colloid.” Calcite (calcium carbonate) is the most common deposited mineral from overlying limestone rocks, so we’ll stick to this mineral example.
As water seeps down into caves, it passes through organic matter and acquires carbon dioxide gas, creating carbonic acid. When carbonic acid interacts with cave ceilings, it dissolves calcite (calcium carbonate) from rock surfaces, creating a calcium bicarbonate solution that slowly drips down. After water droplets disperse and evaporate, a deposit of calcium carbonate is left behind.
Stalactites do not form until there’s an initial drop of water hanging through surface tension, meaning the droplet needs to hang there long enough to deposit a solid mineral around its outer rim. As this process continues, the slow drip eventually forms a tube-like channel (like a soda straw), where subsequent droplets accumulate down, depositing minerals around the rim as they fall.
Fun fact: If you remove a stalactite to inspect its inner structure, you’ll find the hollow tube where the initial drip once was surrounded by concentric rings. The rings, much like those of a tree, reflect various periods of growth (rings containing clay suggest periods of no growth).
Stalagmites are solid throughout and typically grow wider and stronger than their stalactite counterparts. Recent studies show stalagmite shapes are dependent on “how far water droplets fall from their stalactite of origin,” meaning the higher the cave ceiling (or distance from stalactite tip), the thicker the stalagmite will be.
Additionally, the faster calcareous water drips onto cave floors, the less controlled calcite precipitation is over a large surface area. Therefore, speedier drip frequencies tend to result in flowstone formation (flat, smoother surfaces), whereas the slowest drip rates result in candle-like stalagmites. Dome and cone shapes fall somewhere in the middle, with dome stalagmites appearing with faster drip rates than cone stalagmites.
When stalactites and stalagmites meet
When uninterrupted, stalactites and stalagmites form in unison and eventually meet to create one big “column” or “pillar.”
How fast do stalactites and stalagmites form?
Cave stalactites and stalagmites grow about one inch per year, so large structures take a few hundred years to a million years to grow. The overall growth rate depends on how consistent (and undisturbed) the environment is, with temperature, pH, airflow, and rainwater playing large roles over time.
Where to find stalactites and stalagmites?
The most common form of stalactites and stalagmites are found in limestone caves, such as the white chamber of the Jeita Grotto in Lebanon, the Limestone Cave in Yucatan, Mexico, and the Marble Cave in Gadime e Ulët, Kosovo.
Vietnam’s Hang Sơn Đoòng, meaning “cave of the mountain river,” is the largest cave system in the world and contains stalagmites as tall as 70 meters (nearly 230 ft).
As for the world’s longest cave system? That belongs to the Mammoth Caves of Kentucky. The Mammoth Caves are so large–– people describe it as a “labyrinth” with over 400 miles explored and another (possible) 600 miles yet to go.
Tham Sao Hin of Thailand is also remarkable for its pristine towering columns, some reaching near 61 meters (200 ft). However, the largest known stalagmite comes from Cueva San Martín Infierno in Cuba, reaching 67.2 meters long (about 220.5 ft). The world’s largest stalactite reaches 28 meters (about 92 ft) at the Gruta do Janelão in Minas Gerais, Brazil.
Other caves with stalactites and stalagmites around the world include:
- Zhijin Cave, Zhejiang province, China
- Doolin Cave, Co. Clare, Ireland
- Kartchner Caverns, Arizona
- Crystal and Fantasy Caves in Hamilton Parrish, Bermuda
- Škocjan Cave in Divača, Slovenia
- Reed Flute Cave in Guilin, Guangxi, China
- Marble Caves, Patagonia, Chile
- The Gouffre de Proumeyssac (aka “The Devil’s Hole”), France
- Carlsbad Caverns, New Mexico
- Grotte du Grand Roc, France
- The Puerto Princesa Subterranean River National Park, Philippines
- Luray Caverns, Virginia
- Cave of the Mounds, Wisconsin
Caves with lava stalagmites and stalactites:
- Nāhuku (Thurston Lava Tube), Hawaii Volcanoes National Park, Hawaii
- The Cave Vidgelmir (Víðgelmir), Deildartunguhver, Iceland
- Lava Beds National Monument, near Medicine Lake Volcano, California
Caves with ice stalagmites and stalactites:
- Eisriesenwelt Ice Cave, Werfen, Austria
- Ningwu Ice Cave, Ningwu County, China
- Kungur Ice Cave, Perm Krai, Russia
Do stalactites and stalagmites grow in underwater caves?
Stalactites and stalagmites typically grow in dry caves and away from bodies of water. Few exceptions occur when calcified, such as “The Hells Bells” in the El Zapote cave near Puerto Morelos on the Yucatán Peninsula.
Can you touch stalactites and stalagmites in caves?
Theoretically, yes. But you shouldn’t. Speleothems are more fragile than they look and, if broken, would require thousands of years to restore to their original state (plus, they are made up of reactive minerals that you don’t want interacting with your skin oils). For these reasons, most of the world’s stalagmites and stalactites are protected by governments as natural heritage objects. So please look, but don’t touch.
How to remember the difference between stalagmites and stalactites?
There are three easy ways to remember the difference between stalagmites and stalactites:
- Remember the mnemonic: “the ‘mites go up, and the ‘tites come down.” (Just don’t confuse the spelling of “tites” with “tights”).
- “Stalactites hand TIGHT to the ceiling.”
- Associate the letter -g- of “stalagmite” with “ground,” and the letter -c- of “stalactite” with “ceiling.”
How to use stalactite and stalagmite in a sentence?
Use the words “stalactite” and “stalagmite” as singular nouns and “stalactites” and “stalagmites” as plural forms.
- “Pick it up from the center of the square and decide whether you want points up (so they rise like stalagmites) or down (to create a simple puff).” — Forbes
- “Alice studied MA Fashion at the Royal College of Art, which is where she developed this process of turning bodily secretions into stalagmite-esque art.” – Refinery29
- “But then a new focus emerged, one that looks to the island’s landscape—its steep cliffs, stalactite caves, fine limestone crags, and breathtaking sea views from the top.” – National Geographic
- “Using isotopes from Texas cave stalactites, scientists in Texas A&M’s College Of Geosciences studied thunderstorm changes in the Southern Great Plains.” — SciTech Daily
Additional reading for stalactite vs. stalagmite
Looking for more science-y grammar topics? If so, be sure to check out similar lessons by The Word Counter, such as:
- Aluminum vs. aluminium?
- Macro vs. micro?
- Port vs. starboard?
- Possum vs. opossum?
- Prognosis vs. diagnosis?
Test how well you understand the difference between stalagmite vs. stalactite with the following multiple-choice questions.
- True or false?: Stalactites are a type of rock formation found in every cave structure.
- True or false?: Large stalactites and stalagmites are created in a matter of hours.
- Which of the following describes a stalagmite the least accurately?
a. Inverted stalactite
b. Cylinder of calcium carbonate
c. Concrete structure
d. An accumulation of material
- Stalagmites do not grow from _____________.
a. Ceiling drippings
b. The ceiling of a cave
c. The ground of a cave
d. The floors of caverns
- Stalactites do not grow from _____________.
a. Deposition of material
b. The roof of a cave
c. The sides of caverns
d. B and C
- The plural form of “stalagmite” is _____________.
- Other than calcite, stalagmites and stalactites can form from other mineralized water solutions containing ______________.
d. A and B
- The natural cave environment for stalagmites does not require consistent _____________ to grow.
b. Partial pressure of carbon dioxide in mineral solution
c. pH conditions
d. Chemical reactions
- Which of the following structures is least likely to grow on concrete ceilings?
a. Lava stalagmites
b. Limestone stalagmites
c. Ice stalagmites
d. All of the above
- Which of the following stalactites are true speleothems?
a. Lava stalactites
b. Ice stalactites
c. Limestone stalactites
d. Concrete stalactites
- Cave visitors are allowed to touch speleothems under what condition?
a. Must use pants, shirt, or any cloth to protect hands
b. If the structure’s mode of attachment is strong enough
c. When the insides of a cave are already vandalized
d. Never. Leave the speleothems alone!
- Several online sources credit the etymology of stalactite to “Greek stalasso.” We were unavailable to verify this attribution among dictionary sources.
- Various websites allege that amberat, the crystallized urine of pack rats, is a common material of stalactite structures. There are no academic or government resources available to verify this statement.
- Atmatziduo, M. “How sport climbing is helping to revitalize a Greek island.” National Geographic, nationalgeographic.com, 27 Jul 2021.
- Apse, W. “Chemical Weathering: A Great Natural Force.” Owlcation, Maven Media Brands, 24 Apr 2020.
- Britannica, The Editors of Encyclopaedia. “Cave deposit.” Encyclopedia Britannica, 8 Feb. 2016.
- Curl, J. S. “Stalactite.” A Dictionary of Architecture and Landscape Architecture, Encyclopedia.com, 17 Jun 2021.
- Frisia, S., Woodhead, J.D. “Stalactites and stalagmites.” Encyclopedia of Caves (Second Edition), Academic Press, pp. 805–810, 2012.
- Harper, D. “Stalagmite” and “stalactite.” Online Etymology Dictionary, etymonline.com, 2021.
- Heidelberg University. “Unique underwater stalactites.” Science Daily, sciencedaily.com, 24 Nov 2017.
- “How Stalactites and Stalagmites Form.” National Park Service, U.S. Department of the Interior, 2021.
- Kornei, K. “How Stalagmites Get Their Shapes.” The New York Times, nytimes.com, 27 Nov 2019.
- Murray, G. “Alice Potts Turns Bodily Fluids Into Fashion.” Refinery29, refiner29.com, 26 Nov 2018.
- Solomon, M. “How to Wear a Silk Pocket Square.” Forbes, forbes.com, 1 Jun 2016.
- “Stalactite.” The American Heritage Dictionary of the English Language, 5th ed., Houghton Mifflin Harcourt Publishing Company, 2021.
- “Stalactite.” Cambridge Dictionary, Cambridge University Press, 2021.
- “Stalactites, Stalagmites, and Cave Formations.” National Park Service, U.S. Department of the Interior, 2021.
- “Stalagmite.” The American Heritage Dictionary of the English Language, 5th ed., Houghton Mifflin Harcourt Publishing Company, 2021.
- “Stalagmite.” Cambridge Dictionary, Cambridge University Press, 2021.
- “Speleothem.” Lexico, Oxford University Press, 2021.