Anah anticline is a conspicuous structural and geomorphological feature in the central western part of Iraq, which is a flat plain dissected by dense drainage net, some of the valleys cross the anticline; whereas others run on both sides, the axis not being the water divide. The anticline trends almost E – W with length of about 90 km, the northern limb is steep, whereas the southern limb is very gentle; giving monoclinal shape to the anticline. The oldest exposed rocks in the core of the anticline are of Middle Oligocene age, whereas the carapace is built of Early Miocene - Late Oligocene age, all formations consist mainly of limestone. Anah anticline forms the extreme western part of the contact between the Inner and Outer Platforms of the Arabian Plate. Many valleys cross the anticline in S – N trend; the largest one is Chab'bab valley, which exhibits canyon form in some parts with sharp knick point. Many other valleys exhibit knick points too along their courses; through crossing the anticline. The height of the knick points ranges from (3 – 8) m, all are located along one lineament, which is almost parallel to the axis of the anticline. The knick points along the courses of the valleys and the crossing of the anticline by many valleys; forming wind gaps are clear indications for the lateral and vertical growths of the anticline.