Novice geologists often confuse the age of landforms with the age of the rocks that comprise them. For example, Mammoth Cave, in Kentucky, is carved out of Mississippian limestone, deposited in shallow seas some 320 million years ago; however, most of the cave formed over the past 2 million years, eroded by the wet climate of the Pleistocene. In like manner, the Entrada Sandstone, which forms the arches in Arches National Park, was deposited during the Jurassic Period, about 150 million years ago; however, the arches have been molded by wind and water since the onset of Miocene Uplift, which began 20 million years ago.
Towers of limestone, deposited in a Cretaceous Sea, now grace the dry plains of Kansas and the summit of Mt. Everest, earth's highest point, is composed of marine sediments, pushed landward and upward as India collided with the Eurasian plate, 50 million years ago. So, as you gaze upon our modern landscapes, know that they are the product of geologic events and erosional forces, past and present.
