on December 14, 2022
The seabed
Geology and GeographyThe surface of the oceans glistens in dark blue. It is hard to believe that the seabed lies many kilometres deeper in places and that a spectacular underwater landscape is hidden down there. For the seabed is not as smooth as the bottom of a swimming pool: On the seabed there are high mountains, deep
on December 14, 2022
The cycle of water
Geology and GeographyThe water on earth is always on the move. Huge amounts of it are constantly moving – between sea, air and land – in an eternal cycle in which not a drop is lost. The motor of the water cycle is the sun: it heats the water of the oceans, lakes and rivers so much
on December 14, 2022
The cycle of oxygen
Geology and GeographyThe air we breathe contains about one fifth oxygen. This gas is invisible, without smell and without taste – but it is vital for us. Because we need oxygen to gain energy in our metabolism. Without this gas, neither humans nor most animals can survive. Almost all the oxygen in the air is produced by
on December 14, 2022
The blue planet
Geology and GeographySeen from space, the earth’s sphere appears a strong blue. This is because almost three quarters of the earth is covered with water. Although water is transparent in small quantities, from a certain depth it takes on an increasingly strong blue shimmer. Because we see the mighty oceans as blue, the Earth is also called
on December 14, 2022
Delta – watercourse between river and sea
Geology and GeographyMighty and sluggish, the Nile pours into the Mediterranean. Like all large rivers flowing through a plain, the African stream slows down towards its mouth. From the slow flow, the cargo of eroded debris and sand sinks to the bottom and is deposited. With these deposits, the river builds its own obstacle that it has
on December 14, 2022
The Sea Shapes Coasts
Geology and GeographyWherever seawater meets dry land, we speak of a coast. Because the coast is exposed to the force of the sea without interruption, it is constantly changing. How strongly the water gnaws at the mainland depends on the strength of the rock, the height of the waves, the ocean currents and the tides. Gentle ocean
on December 14, 2022
The global wind system
Geology and GeographyThe air masses of the atmosphere flow around the globe: they rise and fall, meet and mix. However, this does not happen in wild confusion, but the winds follow a very specific pattern. This global wind system (also called planetary circulation) is influenced above all by solar radiation and the Coriolis force. The tireless circulation
on December 14, 2022
Bottom formation
Geology and GeographyPlants rarely grow on bare rock. They need a soil from which they can draw nutrients and in which they can form roots. For such soil to develop, weathering is necessary: rain and oxygen, heat and cold, water and wind grind the rock and thus grind even hard granite into smaller and smaller grains. What
on December 14, 2022
Moving earth magnetic field
Geology and GeographyThe earth’s magnetic field behaves much like that of an ordinary bar magnet. However, there are also decisive differences. For example, the earth’s magnetic field is not rigid, but dynamic. Its magnetic poles are constantly in motion. At present, the magnetic south pole is close to the geographic north pole. At about 40 kilometres a
on December 10, 2022
Mountains on the move
Geology and GeographyMighty and rigid mountains rise up into the sky. It seems as if nothing and no one can move them from the spot. But this is not true: mountains are constantly moving – but so slowly that we cannot see the change with the naked eye. The reason for this: the plates of the earth’s