Assessment 2

 1.

What is created when stress applied on a rock causes it to become permanently deformed?

• (A)

  Stratigraphy

• (B)

  Structure

• (C)

  Diagenesis

• (D) All of the above

2. Stress is the force per unit area acting on any surface within a solid such as a rock or grain.

• (A)

  True

• (B) False

• (C) None of the above

3. Considering the example of a single clastic grain buried within the earth, at any given time, what forces may be acting on the buried grain?

• (A)

  Gravity and inertia

• (B)

  Viscous forces

• (C)

  Pressure

• (D)

  (b) and (c)

• (E)

  All of the above

 4.

If the stresses on all parts of a rock grain are the same, the stress field is said to be:

• (A)

  homogeneous

• (B)

  tensional

• (C)

  compressional

• (D) All of the above

 5.

In geology, principal stress is always spoken of in terms of compression, rather than tension.

• (A)

  True

• (B)

  False

 6.

Within the earth's crust, the most common stress situation is:

• (A)

  Uniaxial stress, where two principal stresses are zero and the other is nonzero.

• (B)

  Biaxial stress, where two principal stresses are nonzero and the other is zero.

• (C)

  Triaxial stress, where all three principal stresses are nonzero.

• (D)

  Pure shear stress.

 7.

Strain is a measure of the change in length of any element (such as shape or volume) in a body of rock compared to the original length of that element, which may increase in some directions and decrease in other directions.

• (A)

  True.

• (B)

  False.

 8.

To help simplify analysis of strain, geologists assume that the strain involved in deformation has been inhomogeneous.

• (A)

  True

• (B)

  False

 9.

In naturally deformed rock, the most common type of strain encountered is:

• (A)

  homogeneous strain, where the rock particles remain relatively undeformed and in their original positions.

• (B)

  inhomogeneous strain, where there has been some amount of particle rotation.

 10.

In which type of shear are all particles within a body displaced in one direction?

• (A)

  Pure shear

• (B)

  Simple shear