Difference Between Stalactites and Stalagmites
Stalactites hang down from cave ceilings (think: 'c' for ceiling, or 'tights' that hang). Stalagmites grow up from cave floors (think: 'g' for ground, or 'might' reach up). Both form from mineral deposits left by dripping water over thousands of years. When they meet, they form a column.
Key Takeaways
- Both formations are created by water dripping through limestone rock.
- Memory tricks: StalaCtites = Ceiling, StalaGmites = Ground.
- In rare conditions, stalactites can form from lava (lavacicles) or ice.
Explanation
Both formations are created by water dripping through limestone rock. As water passes through, it dissolves calcium carbonate. When the water enters the cave and is exposed to air, it releases carbon dioxide and deposits tiny amounts of calcite. Over thousands of years, these deposits accumulate into formations.
Stalactites form where water drips from the ceiling. Each drop deposits a ring of calcite, gradually forming a hollow tube (soda straw), then a solid cone as more deposits build up outside. They grow about 0.1 to 10 centimeters per thousand years depending on conditions.
Stalagmites form where water drips onto the cave floor. The splash spreads the mineral deposit wider, so stalagmites are typically broader and more rounded than stalactites. When a stalactite and stalagmite meet, they form a column or pillar.
Things to Know
- Memory tricks: StalaCtites = Ceiling, StalaGmites = Ground. Or: Stalactites hold 'tight' to the ceiling.
- In rare conditions, stalactites can form from lava (lavacicles) or ice.
- Touching formations deposits oils that can slow or stop their growth.