One of the best-known effects of the great heat that lies inside the Earth can be seen in hot, mineral springs that gush out of the surface of the Earth. These are rich in minerals such as common salt, which rise to ‘bitter springs’, and iron, sulfur and magnesia, giving medicinal waters.

Scientists differ in their opinions on how these hot springs began. Some believe they come straight up from underneath and the ground where they were trapped millions of years ago during earth movements. Other scientists think the water began as rain which seeped through the soil, became heated and then rose again.

Perhaps both opinions are correct. It is certain, however, that the waters of these springs have flowed under the soil, become enriched with mineral salts and been heated to boiling point.