The Roaring Falls
Some waterfalls form in mountain environments where the erosive water force is high and stream courses may be subject to sudden and catastrophic change. In such cases, the waterfall may not be the end product of many years of water action over a region, but rather the result of relatively sudden geological processes such as landslides, faults or volcanic action.
The rocks here are sandstone and sometime form a conglomerate which is sandstone with quartz pebbles cemented together. Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Larger white pebbles here are quartz.
Formation of a waterfall flows over a large step in the rocks which may have been formed by a fault line. Over a period of years, the edges of this shelf will gradually break away and the waterfall will steadily retreat upstream, creating a gorge of recession. Often, the rock stratum just below the more resistant shelf will be of a softer type, meaning undercutting, due to splash back, will occur here to form a shallow cave-like formation known as a rock shelter or plunge pool under and behind the waterfall. Eventually, the outcropping, more resistant cap rock will collapse under pressure to add blocks of rock to the base of the waterfall. These blocks of rock are then broken down into smaller boulders by attrition as they collide with each other, and they also erode the base of the waterfall by abrasion, creating a deep plunge pool.
Streams become wider and more shallow just above waterfalls due to the stream flowing over the rock shelf, and there is usually a deep pool just below the waterfall because of the kinetic energy of the water hitting the bottom pool.
Types of Waterfalls
Waterfalls can be classified as to their shape, drop, height and width. Here is a common classification system: Block-the water descends from a relatively wide stream or river, Cascade-the water descends a series of rock steps, Cataract-a large waterfall, Fan-the water spreads horizon ally as it descends while remaining in contact with bedrock, Horsetail-descending water maintains some contact with bedrock, Plunge-water descends vertically, losing contact with the bedrock surface, Punchbowl-water descends in a constricted form, then spreads out in a wider pool, Segmented-distinctly separate flows of water form as it descends, Tiered-water drops in a series of distinct steps of falls, Multi-step-a series of waterfalls one after another of roughly the same size each with its own sunken pool.
NOTE: In order to claim a find on this Earthcache you must: 1. Post a photo of yourself at the Falls with GPS in hand and the Falls in the background. 2. You must also send me an email with answers to the following questions:A. From the list above, what type of falls are the Roaring Branch Falls. B. Estimate the width of the Falls at it's base and C.what is the elevation at the base of the Falls (close to coordinates). NOTE: GPS readings are problematic in this hollow so don't worry about finding the exact spots. Take your photo and elevation reading near the falls. I'm not looking for precision. Not just for the required photo, but be sure to bring your camera for this wonderful geological exhibit of Nature