Table Mountain was formed by a lava flow. Just like water, liquid lava flattens out. Over time, small steams flowed through cracks in the lava forming small valleys.
Ditto what Tyler said. If you go, be sure to walk in to the water flow and follow (go west or left) and you will come to the waterfall. Very pretty and worth the visit.
It's a plateau from an old lava field. As you might imagine, a slow cooling lava field can easily flatten out aside from the cracks that form over time - creating the mirco valleys in table mountain.
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