Half-grabens are faults where a drop-down has occurred due to extension but there is no uplift on the other side. You can get series of half-Grabens where they look like dominoes in the process of falling down. These are more common than Horsts and Grabens.
ROCK FOLDING Rock folding is different than a fault line. Faults are fractured areas, whereas folding happens to ductile rocks. Compression over time leads to folding. The strain rate needs to be low so you don't get fracturing. The two sides of any fold are called limbs. Figure 54 shows some geometry you need to know with regard to geological folding:
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