Question

Describe the mantle ?State its two chief characteristics

Answer 1

mantle is the second layer of the earth which exists at the depths from 100kms to 2900 kms
the upper part of the mantle is a pilable layer over which te crust floats 
this consits mainly of chemicals called silicates 
the mantle forms 16 % of the volume of the earth

Answer 2

The mantle is a layer inside a terrestrial planet and some other rocky planetary bodies. For a mantle to form, the planetary body must be large enough to have undergone the process of planetary differentiation  by density. The mantle surrounds the planetary core. The mantle is surrounded by the crusrt. 
characteristics are-
 Earth's mantle is thought to be composed mainly of olivine-rich rock. It has different temperatures at different depths. The temperature is lowest immediately beneath the crust and increases with depth. The highest temperatures occur where the mantle material is in contact with the heat-producing core. This steady increase of temperature with depth is known as the geothermal gradient. The geothermal gradient is responsible for different rock behaviors and the different rock behaviors are used to divide the mantle into two different zones. Rocks in the upper mantle are cool and brittle, while rocks in the lower mantle are hot and soft (but not molten). Rocks in the upper mantle are brittle enough to break under stress and produce earthquakes. However, rocks in the lower mantle are soft and flow when subjected to forces instead of breaking. The lower limit of brittle behavior is the boundary between the upper and lower mantle.