Which is older intrusion or extrusion?
Lava that hardens on the surface is called an extrusion. The rock layers below an extrusion are always older than the extrusion. There, the magma cools and hardens into a mass of igneous rock called an intrusion. An intrusion is always younger than the rock layers around and beneath it.
Is layer D younger than layer C?
The intrusion (D) cuts through the three sedimentary rock layers, so it must be younger than those layers. The principle of superposition states that the oldest sedimentary rock units are at the bottom, and the youngest are at the top. Based on this, layer C is oldest, followed by B and A.
How do you identify faults in the field?
To correctly identify a fault, you must first figure out which block is the footwall and which is the hanging wall. Then you determine the relative motion between the hanging wall and footwall. Every fault tilted from the vertical has a hanging wall and footwall.
How do you identify a fold in field?
A fold can be recognised in the field when a surface shows direction, sense or dip angle variations. Folds are composed of an axial plane, a fold axis, limbs and a hinge line.
What happens to a road in a normal fault?
A normal fault is a fault in which the hanging wall moves down relative to the footwall. A normal fault is a result of the earth’s crust spreading apart. This often occurs at plate boundaries, but it can happen at faults in the middle of plates also.
What does a normal fault look like?
Normal faults create space. These faults may look like large trenches or small cracks in the Earth’s surface. The fault scarp may be visible in these faults as the hanging wall slips below the footwall. In a flat area, a normal fault looks like a step or offset rock (the fault scarp).
What type of movement does a normal fault have?
normal fault – a dip-slip fault in which the block above the fault has moved downward relative to the block below. This type of faulting occurs in response to extension and is often observed in the Western United States Basin and Range Province and along oceanic ridge systems.
What type of stress is placed on a normal fault?
Tensional stress
What type of earthquake is strike-slip fault?
Strike-slip faults are vertical (or nearly vertical) fractures where the blocks have mostly moved horizontally. If the block opposite an observer looking across the fault moves to the right, the slip style is termed right lateral; if the block moves to the left, the motion is termed left lateral.
What is an example of a strike-slip fault?
The fault motion of a strike-slip fault is caused by shearing forces. Other names: transcurrent fault, lateral fault, tear fault or wrench fault. Examples: San Andreas Fault, California; Anatolian Fault, Turkey.