In the Golden Dawn the candidate is shown a geomancy talisman as an example of Earth Magic. Generally, though Geomancy was focused on divination and has been pretty much universally hated by Golden Dawn students (other than Crowley and his follower Israel Regradie). To be fair, GD geomancy is based on Theomagica by John Heydon which is a mess. When restored to its proper condition geomancy becomes a powerful elemental magic tool. Geomancy is based on 16 symbols which work in a similar binary system to the iChing.   Each symbol is made of four elemental lines from the top down (Fire, Air, Water, and Earth) which are either switched on or switched off.  The elemental lines mean (from the top down)