Il nostro angolo Scienza e Tecnologia


By Alessio Pitteri, Camilla Giacori and Marco Milan, class 3 A

The science teacher grades her students after a Karst workshop at the Postojna caves, Slovenia.

Postojna cavesScience Teacher: Which European countries show Karst features?

Alessio: All the European countries except for Finland, Denmark, and the Netherlands.

Science Teacher: Which is the main feature of a Karst landsacape?

Marco: The lack of hydrographic surface, which creates a dry, rocky, landscapes full of dangers.

Alessio: the formation of limestone caves.

Camilla: Rain water shapes the rocks, which are formed by minerals that are highly soluable in water. Usually, stalactites and stalagmites form in underground caves.

Science Teacher: How are stalactites and stalagmites formed?

Marco: The dripping of water makes calcium bicarbonate turn into calcium carbonate. The deposit creates a stalactite. A stalagmite is formed inthe same way and it often arises just under a stalactite. When both of them join, a stone column is created.

Science Teacher: Why are stalactites and stalagmites black or red?

Alessio: It depends on the presence of zinc.

Marco: Iron and Aluminium hydroxide give colourings which vary from red to yellow.

Science Teacher: Why musn’t you touch stalactites and stalagmites with your bare hands?

Alessio: Because grease prevents their growth.

Camilla: If you do, they will die!

Science Teacher: How does precipitation occur?

Marco: Carbonic acid is formed as rain water passes through the atmosphere and picks up carbon dioxide (Co2), which dissolves into water. When rain water reaches the ground, it may meet soil that provides much more CO2 to form a weak carbonic acid solution, which dissolves calcium carbonate.

CO2 + H2O+CaCO3 <—> H2CO3 Ca (HCO3)2

Science Teacher: Which living organism lives in the Postojna caves?

Alessio: The olm or Proteus anguinus.

Camilla: it is a salamander in the family Proteidae.

Marco: This amphibian is entirely aquautic and lives in complete darkness in its underground habitat.