Faulty Thinking EarthCache
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From this location you can see a number of faults. You have to look north uphill into the Railroad cuts.
From the diagram above (the top one) The term Headwall and Footwall. The headwall is typically the one that has slipped up. There are exceptions (as you can see in the picture) but without getting too complicated we will use that term. The upward slab of a fault. .
Typically faults area clean, and show a simple slice made into the ground. moving the material. However sometimes the ground is put under strain and it stretches, or flexes until the fault slides, or it drags upon the other side of the fault. So one or both sides of the fault drag towards the other side. This is called a drag fold, or drag faulting. (The middle diagram)
Then once and a while when material moves it leaves a pieces of it behind. (see the bottom diagram) Usually typically occurs when a fault has moved for some time, then a piece breaks off and another fault is made leaving the sliver. Sometimes multiple slivers are left. Each new fault moving a bit before another piece breaks off.
Now back to the diagram on top. There are two kinds of faults. Normal faults, and a reverse (thrust) fault. In the normal fault ground is pulling away, or side to side. Causing the faulting to take place. However once and a while a fault is made from two pieces pushing toward each other. One piece is being thrust over the other. That is a reverse or thrust fault. (though we do not have that here)
Logging tasks
Looking NorthWest
1-What side is the Headwall?
Looking North
2-How many faults do you see?
3-Would you describe them as a Normal Fault? Drag Fault? Are there slivers present?
4-Are the headwalls on the same side for all these faults?
Looking at the North East Railroad Cut
5-Do you see evidence of faulting? Describe why you think there is or why you do not think there is a fault there?
Diagrams from : Hintze, L. F., (editor), 1962, Geology of the Southern Wasatch Mountatns and vicinity, Utah: Brigham Young University Geology Studies, vol 9
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