A Permanent Survey Mark (PSM) is a major reference mark placed by surveyors to assist them in repegging land parcels and extending new surveys. They are also used for projects such as road construction, map production and mining development.
PSMs are typically blocks of concrete approximately 200mm square and 300mm deep. They have a brass plaque or metal rod at the centre. Most are placed below ground level and arent visible unless they have been marked with either a metal cover (usually in metropolitan areas) or a witness post and indicator plate (usually in areas being developed).