Oman
Wadi Bani Khalid ...
...is one of the best-known wadis in the country. Its stream maintains a constant flow of water throughout the year. Large pools of water and boulders are scattered along the course of the wadi. As a geographical area, the wadi covers a large swathe of lowland and the Hajar Mountains.
The wadi is easy approachable by car and lies about 200 km away from the Omani capital Muscat .
Wadi is the Arabic & Hebrew term traditionally referring to a valley, but sometimes it refers to a dry riverbed that contains water I lg during times of heavy rain.
1. Morphology and processes
Wadis are located on the gently sloping, nearly flat parts of deserts; commonly they begin on the distal portions of fans and extend to inland sabkhas or playas. In basin and range topography, wadis trend along basin axes at the terminus of fans. Permanent channels do not exist, due to lack of continual water flow. Wadi show braided stream patterns because of the deficiency of water and the abundance of sediments. Water percolates down into the stream bed causing abrupt loss in energy and resulting vast deposition. Wadis may develop dams of sediment which results in change of stream patterns in the next flash flood.
Wind also plays its role in deposition. When wadi sediments are underwater or moist, wind sediments are deposited over them. Thus wadi sediments contain both wind and water sediments.
2. Sediments & sedimentary structures
Wadi sediments may contain whole range from gravel to mud. There is also wide range of sedimentary structures. Thus, wadi sediments are most diagnostic of all other desert environments.
Flash floods represents severe energy conditions and results in wide range of sedimentary structures, including ripples and commonly plane beds. Gravels common display imbrications, Mud drapes show desiccation cracks. Wind activity also generates its own sedimentary structures, large scales cross-stratification and wedge shape cross-sets are present. Typical wadi sequence consists of alternating units of wind and water sediments; each unit range about 10–30 cm. Water laid sediments show complete fining upward sequence. Gravels show imbrication. Wind deposits are cross stratified and covered with mud-cracked deposits. Some horizontal Loess may also present.
3. Deposits
Deposition in a wadi is rapid because of the sudden loss of stream velocity and seepage of water into the porous sediment. Wadi deposits are thus usually poorly sorted gravels and sands. These sediments are often reworked by eolian processes.[3]
Over time, wadi deposits may become "Inverted Wadis" where the presence at one time of underground water caused vegetation and sediment to fill in the wadi's eroded channel, to the point that previous washes appear as ridges running through desert regions.
4. The Cache
In order to log this cache you have to answer the following questions and send me the answers via Messenger or email (see my profile):
1. What kinds of sediments contain wadi sediments? Describe them.
2. What are flash floods and what are their impact on a wadi?
3. What is the height of the bridge from which locals & tourists are jumping into the water?
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Enjoy the cool fresh water of Wadi Bani Khalid!
Sources: Wikipedia
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