Karst is a complex landscape sculpted by water. It is a distinctive topography in which the landscape is largely shaped by the dissolving action of water on carbonate bedrock (usually limestone, dolomite, or marble). This geological process, occurring over many thousands of years, results in unusual surface and subsurface features ranging from sinkholes, vertical shafts, disappearing streams, and springs, to complex underground drainage systems and caves. In this case limestone is the predominant feature.
Karst is widespread on the peninsula of Qatar in the Arabian Gulf, including depressions, sinkholes, caves, and solution hollows. More than 9700 large and small depressions, and several exposed sinkholes and caves are known. Field and air-photo studies indicate that the depressions, sinkholes, and caves of Qatar are genetically related sinkholes. Karst is concentrated mainly within the limestone, dolomite, gypsum, and anhydrite horizons of the Eocene Rus and Dammam Formations.
Over a period of time a combination of groundwater and rainwater have reacted with these relatively soft surface and sub-surface rocks, dissolving gypsum and limestone. Generally, it is believed that this has come about at the interfaces between different characters of rock.
This has created underground cavities, some of which have had their ceilings collapse, exposing the interior of the dahl, or sinkhole as in Dahl Al Hammam in Doha. This dahl has now been incorporated within a small park that is open to the public at all hours.
This sinkhole has an oval opening, oriented in a NE-SW direction. The vertical depth is 15m at an inclination of around 25 degrees. It is the only sinkhole containing saline water at a depth of 15 m. The hole is connected to the Arabian Gulf, which is 4 km east of the sinkhole. Several types of small fish live in the water, and the tidal fluctuation of the water table is 30 cm.
The Musfer & Mudhlem Caves, which are considerably larger and deeper, can also be visited and are indicated as traditional caches on www.geocaching.com as GC1691T and GC16456 respectively. These are both situated in the wilderness and can be reached with a normal saloon car.
In order to claim the earthcache you need to e-mail your answers to the questions below to the cache developer at cincolcc(at)gmail.com. You do not have to enter the enclosure to answer the questions.
1. The approximate length and width of the opening.
2. The number of light beacons INSIDE the fenced off area.
3. An optional photograph with dahl in background holding GPSr. {Upload with log}
NOTE: You may log your visit prior to approval, but e-mail submissions that do not meet the above criteria will be deleted.
Internet information is sparse. The 2 known sources are:
http://www.catnaps.org/islamic/geography.html#top
http://www.caves.org/pub/journal/PDF/V64/v64n2-Sadiq.pdf
FTF goes to mrunte
