Ozone layer

The ozone layer filters the Sun´s harmful UV radiation, therefore it is indispensable for life on Earth.

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How lakes disappear

On a geological time scale lakes are short-lived.

Folding (intermediate)

Lateral compressive forces cause rocks to form folds. This is how fold mountains are formed.


Waterfalls form where the river flows over a steep precipice in its course.

The Pompeii before time

There is a little village in Northern Hungary in Central Europe that is a hiding place for a...


The last Ice Age ended about 13 thousand years ago.


An earthquake is one of the most devastating natural phenomena.


The circumference of the Earth has already been calculated in ancient Egypt. The calculations...

The Gregorian calendar

Developed nearly 500 years ago, it is a variant of the Julian calendar. Today it is the most...

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