Like most caves in the world, the Marble Arch Caves are situated in a limestone area. Limestone is a sedimentary rock made up of bits of animal shells compacted together over millions of years.

CONNOR: Good thinking! I read a bit about limestone on the bus journey. Limestone is a sedimentary rock created by layers of skeletons and shells of sea creatures found in ancient, warm ...

Why it's incredible: The marble walls reflect the turquoise color of the water in the cave, tinting them blue. The Marble Caves are natural rock formations with curved walls covered in swirling ...

The Marble Caves are natural rock formations with curved walls covered in swirling mineral patterns. They sit on the shores of General Carrera Lake, a glacial lake in southern Chile. The lake ...