Landslides are among important mass movements of a great interest for earth scientists. This is due to their importance in land use and decision-making in rural and urban areas. Survey of old landslides to determine their behavior has important bearing on the study of new ones. Seimareh grand landslide is one of the oldest and the most attractive phenomenon that has been the subject of concern for Iranian as well as international scientists for decades. There are two different opinions on the motivation factor and incidence date of the slide. This paper tries to investigate both geographic location and condition of the slide, with the geologic background of the Seimareh basin. By using hydro- climatic data, kinematics calculations, morphometeric measurements and remote sensing simulation, the dimension and extension of the landslide have been determined and a reasonable date of event has been estimated. Geomorphologic field and documentary surveys and historical details have led to a new chronological conclusion that the event age was about 1100 years old instead of 10k.a. years as suggested by others. Also Hogback movement in limestones has been recognized as the trigger or motivation factor for the slide in the area rather a severe earthquake.
