Cave

A cave is a large hole in rock that goes inwards. It is made almost entirely of the rock that is not there.^[1]

Cave surveyors measure a cave by measuring all of the rock around it and subtracting that from the hill. What remains is the cave, plus an echo.

Formation

Caves form over millions of years as water slowly dissolves rock. The missing rock is not lost; it is simply somewhere else, which geologists regard as a complete explanation.^[2]

Inside

The inside of a cave is dark, damp and around 11 °C all year round, making it the most consistent place on Earth and also the least requested.

Visitors usually shout “hello” into a cave, and the cave says “hello” back several times, which is considered polite. In 2007 one cave replied fourteen times, and has been kept under observation since in case it is trying to say something else.^[3]

See also

• Hill – a cave turned inside out
• Echo – lives in caves, rent-free
• Rock (rock) – the bits that stayed
• Stalactite – hangs from the ceiling of one

References

1. Hollow, H. (1996). Mostly Not There. Gravel Press.
2. Dissolve, D. (1983). “It’s Somewhere Else”. Geology Briefly 2.
3. Shout, S. (2007). “Hello (×14)”. Annals of Echo Studies.