Karst & Sinkhole
Musfer Sinkhole is the official name of a karst cave in Umm Al Shabrum, central Qatar. This sinkhole is one of the karst features. Other karst features include depressions, caves, and solution hollows. Karst is a distinctive environment characterized by landforms that are the product of dissolution of surface and subsurface rock by natural water to a greater extent than in other landscapes. It occurs both as surface and underground features. Several substantial caves are known in Qatar, but many have probably been filled with blown sand, or have collapsed to produce some of the thousands of depressions or dolines.
Karst in Qatar occurs as three types: sinkholes, simple depressions, and compound depressions. Simple depressions are those with a single center. Compound depressions have more than one center, and are large and rectangular or irregular in shape. These depressions seem to have formed through the amalgamation of several simple depressions. More than 9700 large and small depressions, and several exposed sinkholes and caves are known.
Sinkholes are concentrated in the central and northern parts of Qatar. Musfer sinkhole large karst collapse feature is expressed by a 1.5 by 0.5 km surface depression up to 20m deep. It has an opening of 12 x 4.5 m and is at least 100 m deep, though filled with sloping loose sand at the bottom. Gypsum layers of the Lower Dammam Unit and the Rus Formation occur at the bottom of this sinkhole. The cave walls are composed of the upper Dammam dolomite & limestone unit and the lower Dammam laminated shaly & silty unit. It is suspected that this sinkhole is part of a much larger cave system. 
How it is formed 
Downward percolating rain water dissolves carbonate rock and causes collapse of the overlying rock. Large depressions (sink holes) and caves form over fracture or fault zones which drains the water away. In humid climates this process forms a typical karst landscape with frequent large sinkholes often filled with water in a subterranial drainage system. Initial dissolution took place in the Pliocene when the climate changed to more humid and sea level rise caused high ground water levels. The karst features were caused by the dissolution of Rus Formation gypsum beds during humid and wet periods in the Pliocene and Pleistocene (Hofuf Formation deposited in Pliocene)
The caves and sinkholes of Qatar is thought to have been formed in the Mid Pleistocene (325,000-560,000 years ago) when the climate was humid.
Directions: [Note: from personal experiences]
We left Doha (to be exact Villagio Carrefour parking lot) around 05.17 AM, heading for Salwa Road. About 19.4 km from Salwa Interchange, we turn right to road leading to Umm Ash Shubrum. Approaching this turn off, you will see the Earth Satellite Tracking Station. The cave is to the right near the station. Entering turn off, you will have intersection. Both left and right turns can lead you to the cave. We chose turning left which seemed a good decision as the road is new and in good condition. (later when heading back to Doha from cave we come to know that we could have turned right for easy navigation although road was not as good as the left option; if you take the turn-right then left option you will see camel farm at the road intersection after about 4km). About 600m from the intersection we took right turn to another asphalt road. We drove around 4.1 km before making right turn at the road intersection. We turned right to asphalt road with full of potholes that we opted to drive alongside the road on dirt track. Driving about 700m from intersection, we made a left turn to not-so-obvious dirt track leading to the cave. The cave is located on an area with scattered scrubs after the power line. So make sure that you are crossing underneath power line. It took us nearly 850 meters from thepotholed asphalt road to the cave.
There is nearby sinkhole (called Mudlem Sinkhole or Dark Cave), near Earth Satellite Station, which is ~150 m deep, filled with sloping loose sand and brackish water at the bottom. The hole has an opening of 15 m in diameter. The entrance, however, had been closed.
For safety reasons, Musfer Sinkhole is chain-link fenced; Normally closed (but not locked) a small gate is provided for access. As you start going downward the cave, you will feel temperature start decreasing and humidity increasing. No particular pathway to go to the bottom of cave; just step on stones. What interesting is that we can see layers of formation at the cave wall, and find trail of motorcycle tire (yes, motorcycle tire trace), track of bettle route (or may be small snake, I don’t know), feces of animal, and cuspid. There is a dark small gap at the bottom but we did not have courage to pass through it…..is it linked to a bigger cave system?
Turn-off Umm Ash Shubrum 25 8’14”N 51 13’47”E
Musfer Sinkhole 25 10’30”N 51 12’41”E
- “MIDDLE PLEISTOCENE KARST EVOLUTION IN THE STATE OF QATAR, ARABIAN GULF” ABDULALI M. SADIQ AND SOBHI J. NASIR (Department of Geology, The University of Qatar)
- Cave Desert Rose Field Trip, October 2008 (http://www.qnhg.org)