Birth of a Mountain
Despite its timeless appearance, Lookout Mountain today bears little resemblance to its past. The key to understanding the mountain's origin is to realize that Lookout and its neighbors were not so much thrust up in relation to the land around them, but rather, the land between the mountains was eroded down to form valleys on either side.
Beginning around 600 million years ago, this region was covered by a vast, shallow sea teeming with tiny marine organisms whose remains were later compressed into the limestone beds of Lookout Mountain. (If you look carefully at the limestone exposed at the Eagles Nest or inside Ruby Falls, you may be able to find the fossilized remains of some of these creatures.) Later, as the landscape slowly changed to one of swamps and rivers, layers of mud were compressed into shale, sand into sandstone, and plants and organic debris into coal.
About 250 million years ago, a collision between the North American and African continents created the Appalachian mountains. The uplift, less violent in the Chattanooga region than elsewhere, bent and gently folded the layers of rock into wave-like patterns. In the crests of these waves, called "anticlines," the rock was highly fractured and easily invaded by water, eroding the more soluble limestones and cherts beneath. However, in the "synclines" or downward waves, fewer fractures were exposed to the elements. The rock which would one day become Lookout Mountain, protected by a syncline, remained intact as the land eroded to each side to form the Chattanooga and Lookout Valleys. The downward bow of the syncline is still visible in the limestone bluffs across from Moccasin Bend and in tilt of the rock in many places on the mountain, which tends to be downward, into the hillside.
Topping the north end of the mountain today, forming dramatic cliffs or palisades, is the sandstone cap which protects the rock beneath from the forces of erosion. Below is a layer of shale and two massive layers of limestone, the Bangor and Monteagle, separated by a layer of Hartselle sandstone. Sandstone debris hides the limestone along the majority of slopes, except at the northern end where the Tennessee River has removed this veil.
The long process of erosion continues to this day. In the enormity of geologic time, an expanse of millions of years in which the existance of man is only a recent phenomena, even a mountain is not immortal. Given time, the protective cap of sandstone will crumble, water will eat away the shale and limestones beneath, and Lookout Mountain will slowly disappear into a new and unfamiliar landscape yet to come.