Table 3.1

Name of the Layer	Chemical Composition	Depth	Density	Physical Property
A. Crust	Crustal material	5-70 Km.		Solid State
1. Upper SIAL	contains lighter elements like Si,
2. Lower SIMA	O, Al, Ca, K, Na, etc... Feldspars
	(Anorthite, Albite, Orthoclase) are common		2.75 – 2.90
	minerals in the crust
	(CaAL2Si2O8, NaALSi3O8,
	KALSi3O8).
B. Mantle	is made up of Si and O, like the	35-2900		Some properties of
3. upper mantle (From	crust, but it contains	km.		solid, some plastic.
Moho to 410 km)	more Fe and Mg. Thus, Olivine			Near the melting point
4. transition zone (410–	(Fe2SiO4-Mg2SiO4) and pyroxene		3.4-5.6	their behavior is like
660 km),	(MgSiO3-FeSiO3)			solids heavy
5. lower mantle (660–	are abundant in the mantle
2891 km)

C. Metallic Core of Barysphere

6. Outer Metallic Core

7. Inner Metallic Core

NIFE

(Nickel + Ferrous or Iron)

Barysphere

(Heavy Metallic rocks)

2900 –

5150 km

5150 –

6378 km

5.10 –

13.00

Liquid or in plastic state Rigid because of tremendous overlying pressure

4. Crust and Mantle vs. Lithosphere and Asthenosphere

Lithosphere, asthenosphere, and mesosphere represent changes in the mechanical properties of the Earth. Crust, Mantle and Core refer to changes in the chemical composition of the Earth.

The lithosphere (litho: rock; sphere: layer) is the strong, upper 100 km of the Earth. The lithosphere is the tectonic plate (we talk about it in plate tectonics). The asthenosphere (asthenos: weak) is the weak and easily deformed layer of the Earth that acts as a “lubricant” for the tectonic plates to slide over. The asthenosphere extends from 100 km depth to 660 km beneath the Earth's surface. Beneath the asthenosphere is the mesosphere, another strong layer.