Geology is all around you in Oman in a way that’s matched by few other places on earth. For professional geologists, the country is one of the most interesting on the planet, and even casual visitors cannot fail to be intrigued by the spectacular rock formations which fill every corner of the Hajar mountains, where the lack of vegetation and soil cover leaves milllions of years of complex geological processes exposed, often with textbook clarity.
Much of Oman’s geological interest (and, by extension, its spectacular mountain scenery) is the result of its location at the southeast corner of the Arabian continental plate where it meets the Eurasian (aka Asian) oceanic plate. As the Red Sea grows wider, Oman is being pushed slowly north and forced underneath the Eurasian plate (a rare example of a continental plate being “subducted” by an oceanic plate), a geological pile-up which has created the long mountainous chain of the Hajar.
Most of the rocks now making up the Hajar mountains were actually formed underwater. As the Arabian plate was driven underneath the Eurasian, large masses of what was originally submarine rock have been pushed on top of the mainland (“obducted”), sometimes travelling hundreds of kilometres inland – which explains the incongruous abundance of marine fossils found buried near the peaks of some of Arabia’s highest mountains. Most of the main part of the range is made of up various types of limestone, ranging from older grey and yellow formations through to outcrops of so-called geological “exotics” – pale, whitish “islands” of younger limestone, such as Jebel Misht and Jebel Khawr, north and south of Al Ayn respectively.
Surrounding the limestone are Oman’s celebrated ophiolites – rocks from the oceanic crust which have been lifted out of the water onto a continental plate. These are of particular interest to geologists in that they reveal processes which are normally buried kilometres underwater. They also provide Oman with one of its most distinctive landscapes, forming the fields of low, irregular, crumbling red-rock mountains which you can see along the Sumail Gap, around the Rustaq Loop and in many parts of the Eastern Hajar.
If you’re interested in exploring further, pick up a copy of Samir Hanna’s Field Guide to the Geology of Oman.