earth

Geography gives answers to the question: where does earth come from, and the earth layers? How did they appear? What are vulcanos? Why is there erosion? Where do oil and gas come from, and what is chalk? etc.


The composition of the earth crust

Our earth is mainly composed of two components:
  1. Organic material (humus with all kinds of nutrients)
  2. Inorganic material; the various kinds of stone (like sand; they contain minerals)
The pH-value can vary: stone of the type of 'granite' has a bit lower pH, is a bit more acid, while Calcium carbonate layers are more basic, so with a bit higher pH value.

The upper layer of earth where we find rivers, seas and oceans, mountains and living creatures, has the following composition:

ELEMENTS PERCENTAGES
Oxygen
47
Silicium
28
Aluminium
8
Iron
5
Calcium
3,5
Sodium
3
Potassium
2,5
Magnesium
2
Other elements
1


The very dominating presence of Oxygen and Silicium in eart layers is due to the sand that is highly built up of SiO2 and its derivates.