What factors are involved for a rock to behave as a brittle ...

[washai]

What factors are involved for a rock to behave as a brittle substance, and what factors cause it to
  behave plastically? What will be an ideal response?

Question 2

What happens first when a stress is applied to a rock? What two things could happen if the stress
  continues to the next step? What will be an ideal response?

[mjbamaung]

Answer to Question 1

Some rocks are more likely to behave as a brittle substance, and others are more likely to behave
plastically. A small stress applied over a long period is more likely to cause plastic deformation then a
large stress applied rapidly. A rock is more likely to behave plastically under higher temperature and
pressure conditions, such as in the mantle, than it is at lower temperature and temperature such as in
the crust.

Answer to Question 2

When a stress is applied to a rock, it undergoes elastic strain. Elastic strain is temporary; if the stress is
removed, the deformed material returns to its original shape. If the stress continues beyond the rocks'
elastic limit, the rocks will behave in one of two ways: They will either break like a brittle solid, or
they will undergo plastic strain. Rocks do not recover from plastic strain or fracture.

[washai]

Great answer, keep it coming

[yeungji]

TYSM