Awash Falls EarthCache
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Forty million years ago Africa and the Arabian Peninsula were joined in a single land mass. At that time the land mass began to stretch, fracture and eventually begin to break apart. Eventually this stretching and breaking formed deep troughs or rifts which are known today as the Red Sea, Gulf of Aden and the Great Rift Valley. The Great Rift Valley began forming about 10 million years ago and extends from Ethiopia southwards through Kenya, Uganda and as far south as the Zambezi River in Mozambique.
The Awash River flows for over 1,000 km through Ethiopia. Its headwaters are in the hills west of Addis Ababa and flows southwards to where it is dammed to form Lake Koka then north eastwards across the Afar Desert where it drains into Lake Abbe. It is the only river that is entirely within the borders of Ethiopia, a land-locked country.
Rivers naturally try to reach equilibrium gradient which is equal to its base level or the level of the body of water into which it flows. For most rivers this is sea level, but in the case of the Awash, this is Lake Abbe. Rivers attempt to reach their equilibrium by eroding upstream towards its headwaters. Waterfalls are a result of this erosion when a river gradually erodes away a “softer” soil to expose a “harder” rock under the river bed.
The Awash Falls which lie about one-third along the river, are at the point where three of Earth's tectonic plates meet and are pulling away from each other. The pulling apart will eventually result in the formation of a new ocean basin.
The falls have gradually moved many kilometers upstream forming the gorge that lies downstream from the falls. At their current location, the falls have reached a fault line and widened themselves producing a small gorge at a right angle to the main river course.
To get credit for this geocache complete the following two tasks:
1) Count the number of distinct falls that cascade over the lip and into the river below.
2) Most of the falls are approximately the same height. Estimate the height of the falls. (The Geocache’s coordinates are about 10 feet or three meters above the top of the falls. One way to make an estimate is to take an elevation reading at this point then walk to the shore of the river. The elevation at the coordinates minus 10 feet or three meter minus the elevation at the shore will give an approximate height of the falls.)
Source; Awash National Park, Ethiopia by Frances Williams, 2012
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