 Three prominent, columnar jointed, cliff-forming lava flows can be seen on North Table Mountain, one exposed part way up the northwest slope, and two that form its cap.The Ralston Dike, a body of intrusive monzonite located about to the northwest, probably represents the volcanic vent from which the flows erupted.The flows are about 62 to 64 million years old according to radiometric dating, which places them in the early Paleocene epoch.