Part A - Identify fault type Some terminology related to faults originated from the mining industry. • The hanging wall block is the rock above the fault where miners would hang their lantern. • The footwall block was where they would walk at the bottom of the tunnel below the faultzone. Which of the diagrams below corresponds to the faulting style you observed in the chalk outcrop?
Part B - Identify fault type II Each basic style of faulting not only has a name; it is also associated with particular tectonic environments that possess common characteristics. Let's review some terms that describe the basic styles of faulting and their typical tectonic environments: Main fault types: 1. Dip-slip: faults that move primarily parallel to the dip (or inclination) of the fault plane: 1. Normal Fault: a dip-slip fault where the hanging wall moves down relative to the footwall. 2. Reverse Fault: a dip-slip fault where the hanging wall moves up relative to the footwall 2. Strike-slip: faults that move primarily horizontal and parallel to the strike of the fault plane. Main tectonic settings: 1. Tensional or extensional: when the principal stresses cause the crust to stretch apart. This setting is characterized by normal faulting. 2. Compressional or collisional: when the principal stresses cause the crust to smash together and thicken. This setting is characterized by reverse faulting From the list of terms below, choose the ones associated with the fault you observed in the Gigapan image. Select the three that apply.
compressional environment
tensional environment
normal fault
reverse fault
shortening of the crust
extension of the crust
Instructions for Part C: 1. Zoom into the lower part of the Gigapan image (near the base of the fault in the outcrop). You will see small, similarly sized figures on each side of the fault. 2. You will use the figures to estimate displacement. Part C - Estimate the displacement on the fault Measuring the movement of blocks along a fault helps geologists evaluate earthquake magnitudes and consider other Earth processes that pose a threat to humans. • Fault displacement is the physical length one side has moved relative to the other. • The magnitude of fault displacement changes along a fault and over time, although outcrop measurements provide a useful snapshot of fault activity. In this part, you will estimate the displacement of this fault using one of the small plastic dolls near the bottom of the outcrop. Assume the dolls are each 4 centimeters tall. Measure the extent of displacement by using the height of one of the dolls as your scale. How much displacement (in meters) has occurred? Note that: 1 doll = 4 cm 1 meter = 100 centimeters
0.4 meters
40 meters
4 cm
4 meters