rock deformation

• the Earth’s crust is divided into plates, known as tectonic plates, and these plates move due to the convection currents in the Earth’s interior.
• Plate movements - The movement of the plates depends on the boundaries between them
• Convergent boundary - the plates move or collide to each other.
• When the plates move away from each other, they are in a divergent boundar
• Finally, when plates slide past each other, they are in a transform boundary
• Plate movements cause rocks to be deformed due to compressional stress at convergent boundaries, tensional stress at divergent boundaries, or shear stress at transform boundaries. Due to these stresses, rocks experience changes in volume and shape.
• Compressional stress causes rocks to be squeezed to each other
• Tensional stress pulls rocks apart
• shear stress causes rocks to slide opposite each other.
• When subjected to stress, rocks can deform by either breaking (fracture) or bending (fold).
• Since the pressure and temperature are low at the Earth’s surface, rocks tend to break or fracture when subjected to compressional and tensional stresses

  This means that the pressure exerted in the blocks of rocks exceeds the rock's internal strength.
• Fractures can either be a fault or a joint
• A fault is a break in the rock where there is considerable movement on the fracture surface while
• a joint is a break where there is no considerable movement.
• Dip-slip faults involve the vertical movement of the blocks of rock.
• These movements are described based on the direction of the motion of the hanging wall with respect to the footwall.
• A hanging wall is the block of rock that rests on the fault plane
• a footwall is the one below the fault plane.
• ip-slip faults can either be a normal or a reverse fault
• A normal fault is caused by tensional stress it is characterized by the hanging wall moving downward with respect to the footwall
• A reverse fault, wherein the hanging wall moves upward, is formed by compressional stress.
• Strike-slip fault involves a horizontal movement of blocks of rock and is caused by shear stress.
• Deep within the crust, where pressure and temperature are high, rocks are plastic-like; thus, they do not break but they tend to bend or fold. When rocks in this area are compressed, they become thicker. When rocks become thinner, they are pulled apart.
• When blocks of rock are bent upwards, they form anticline structures.
• Synclines are formed when blocks of rock bend downwards.
• A slightly bent rock from the parallel undeformed layers forms monoclines.
• • Compressional stress is associated with the convergent plate boundary that causes rocks to be squeezed to each other.
• Tensional stress is associated with the divergent plate boundary that causes rocks to be pulled apart
• • Shear stress is associated with the transform plate boundary that causes rocks to slide opposite each other.
• • Movement of plates leads to rock deformation such as fracture and fold due to stress.
• • A fracture is a break in the rocks and can be classified as a fault or a joint depending on the amount of movement. A fault can either be a dip-slip or a strike-slip fault.
• A fold is a bend in the rocks and can be classified as anticline, syncline, or monocline