Wabar Craters - The Site

The Site

The Wabar site covers about 500 by 1,000 meters, and the most recent mapping shows three prominent, roughly circular craters. Five were reported by Philby in 1932, the largest of which measured 116 and 64 meters wide. Another was described by the 2nd Zahid expedition and is 11 meters wide: this may be one of the other three originally described by Philby. They are all underlain by a hemispherical rim of "insta-Rock," so called because it was created from local sand by the impact shock wave, and all three are nearly full of sand.

The surface of the area partly consisted of "Insta-Rock" or "impactite", a bleached-white, coarsely-laminar sandstone-look-alike, and was littered with black glass slag and pellets. The impactite featured a form of shocked quartz known as "coesite", and is thus clearly the product of an impact event. The impact did not penetrate to bedrock but was confined to local sand, making it particularly valuable as a research site.

The presence of iron fragments at the site also pointed to a meteorite impact, as there are no iron deposits in the region. The iron was in the form of buried fist-sized cracked balls and smooth, sand-blasted fragments found on the surface. The largest fragment was recovered in a 1966 visit to Wabar and weighs 2.2 tonnes. It is known as the "Camel's Hump" and was on display at the King Saud University in Riyadh until it became the entry piece for the new National Museum of Saudi Arabia in Riyadh.

The sand was turned into black glass near the craters, and pellets of the glass are scattered all over the area, decreasing in size with distance from the craters due to wind-sorting. The glass is about 90% local sand and 10% meteoritic iron and nickel.

The layout of the impact area suggests that the body fell at a shallow angle, and was moving at typical meteorite entry speeds of 40,000 to 60,000 km/h. Its total mass was more than 3,500 tonnes. The shallow angle presented the body with more air resistance than it would have encountered at a steeper angle, and it broke up in the air into at least four pieces before impact. The biggest piece struck with an explosion roughly equivalent to the atom bomb that leveled Hiroshima.