OUR EARTH ncert_CLASS7

• EARTH crust is consist of SiMa & SiAl
• CRUST : outer surface of Earth
• SiMa : Oceanic Crust consist of Silica and Magnesium 
• SiAl : Non-Oceanic crust consist of Silica and Alumina 

• CLASSIFICATION OF EARTH'S SURFACE : the outermost surface is called as CRUST ,while the second surface which after the crust is LITHOSPHERE , after lithosphere its MANTLE and after that the last surface is called as INNER CORE
• HAVE YOU EVER OBSERVED THE SMALL CRACKS IN YOUR HOME WALLS ??  :       this is because The LITHOSPHERIC PLATES which moves around very slowly i.e few millimeter every year ,and it is because the movement of molten magma inside the EARTH .
• The forces behind this movement of surface of the Earth is ENDOGENIC & EXOGENIC Forces