Origin of Some Limestone and Gypsum Natural Bridges at Northern Iraq

The present study investigates the location and origin of some natural bridges in northern Iraq. They have been founded in two geological formations, the Sinjar and Al-Fatha formations. The rocks are consisting the bridges are in limestone and gypsum respectively.
The natural bridges have usually been considered as temporary phenomena with a short life span and, in general, have either major or minor sizes as in the case of the present study.
The rainfall and the underground water dissolved both the limestone and the gypsum rocks, which are considered classically as highly soluble rocks. The dissolution of rocks, especially their sub-surfaces, caused an underground tunnels and channels and parts of their roofs would collapsed, while the uncollapsed roofs, subsequently constitute natural bridges. The present study concluded that the origin of natural bridges is karstic, but other origins could be invoked. Usually the natural bridges at the present time considered as natural monument, which must be preserved and located on maps so that they could be used as tourists attraction sites.