They are similar to chronicle fragments from Divination, and will only appear when you come within close range of them, granting 10 Divination experience when caught.
Memory Location
In the troll camp east of the entrance
Along the path south of the troll camp
Along the path to Zarador
The ogre camp east of Zarador
Up the ladder south of Zarador
Graardor's camp southwest of the same ladder
Graardor's "secret weapon" camp to the east
The plateau south of the cyclops camp
Back down the ladder, Bork's camp east of your camp