Named proportion to Saq Mountain in Qassim area, ranging in thickness from 400 m in Qassim region in the Southern part to 700 m in the North-Eastern part. It is consists of sandstones belonging to the Cambrian and Ordovician Era, covering the basement rocks, Saq Sands is generally consolidated, and consists from medium to coarse sand grains, and it is clear from the shale and contain aggregates of large sizes at the base of Formation , it is divided into two members, Al-Rasha member at the bottom Late Cambarian in age and sajir member belonged to the late Early Ordovician at the top.