Five hundred million years ago, in late Cambrian times, the earth warped down and the LaMotte sea flooded all of Missouri, but did not completely cover the St. Francois Mountains. The igneous knobs of the mountains eroded, grains of sand settled on the sea floor, and consolidated into LaMotte Sandstone, the first layer of sedimentary rock in Missouri's geological column. The LaMotte formation, two to three hundred feet thick, spread out across the whole of Missouri, but is only exposed east of the St. Francois Mountains. Then wind and water eroded the rock into amazing forms. |
