What causes stalagmites and stalactites in caves?

Stalagmites and stalactites form in caves through the deposition of minerals from dripping water. When water carrying dissolved calcium carbonate drips from a cave ceiling, it leaves behind small deposits as carbon dioxide escapes. Over time, these deposits build up to form stalactites, which hang from the ceiling. If the droplets fall to the cave floor, they create stalagmites, which grow upward. This process occurs slowly, often taking thousands of years to form large formations.