Answer
When subjected to differential stress, shale is more likely to fold or flow rather than fracture compared to limestone. This behavior is primarily due to the differences in their composition and mechanical properties.
Work Step by Step
Shale is a fine-grained sedimentary rock composed of clay minerals and other fine-grained materials. It has a layered structure with weak bonding between its individual particles. The clay minerals in shale are relatively ductile and can undergo plastic deformation when subjected to stress. This plastic behavior allows shale to deform and flow under pressure, resulting in folding rather than fracturing.
On the other hand, limestone is a sedimentary rock primarily composed of calcium carbonate (calcite) minerals. Limestone is generally more brittle compared to shale due to its crystalline structure and the presence of calcite. When subjected to stress, limestone is more prone to fracture and break along planes of weakness, such as bedding planes or fractures within the rock.
