You have chosen the South Eastern Area of Sosaria. You now see 4 more pictures showing more details of that area. Find the location where your map is and note the rune number on the map (for example: A1, B7, C16).

Go to Arx Draconis and enter the rune library. Find the rune you need and recall off of it. You will appear in the spot right next to where your chest is buried. Dig and you will locate your chest. Happy hunting!