These speleothems (cave formations) are similar to stalactites, but instead of an icicle shape, they are long and straight. Why?
Answer:
These are a type of cave formation known as soda straws. They are thin, hollow tubes of calcite, and they grow as water flows through the inside. The water slowly adds tiny bits of calcite to the bottom, making the tube longer. Eventually, the tubes become plugged, and the water starts flowing over the outside. That causes them to grow wider, changing into stalactites.
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