Interior of earth

1. INTERIOR OF THE
EARTH’S CRUST
By Satvik Lahiry (Bhattacharya)
Class VII-F, Roll no.30

2. WHAT IS EXACTLY THE CRUST ?
• The crust or the lithosphere is the thinnest of all layers of the earth. It is formed by
rocks and minerals . It is also the outermost layer of the Earth.

3. THE LAYERS OF CRUST
• The crust of the Earth can be broadly categorised into two types
• UPPER CONTINENTAL CRUST or SIAL : It is composed of silicon and aluminium
and hence termed as SIAL.
• LOWER OCEANIC CRUST OR SIMA: It is composed of silicon and magnesium and
hence termed as SIMA

4. FEATURES OF THE EARTH’S
CRUST
• The depth of the upper continental crust is 35-40 km whereas the depth of the lower
oceanic crust is 5-8 km.
• The upper continental crust is composed of silicon and aluminium and hence called
SIAL
• The lower oceanic crust is composed of silicon and magnesium and hence called
SIMA.
• The density of the upper continental crust is 2.7 gm/cubic centimetre whereas that
of the lower oceanic crust is 3gm/cubic centimetre.

5. DIFFERENCE BETWEEN SIAL AND SIMA
SIMA
SIAL

6. The End