Scattered fragments

Answer from: none
There are 4 maps that can be assembled from pieces. The locations of the pieces are given below:

Map fragment - Northern Coast locations:
The first map piece is received with the quest.
Mudhold Fasting, in a chest just past the arrow traps.
Mudhold Fasting, in the deepest part.
Reward: Dvergan Greaves

Map fragment - Scuttle Beach locations:
Given by Aubrey Gilcrest after collecting the previous treasure
Undersea Fasting, chest in the westernmost room
Undersea Fasting, chest on a walkway reachable from the tome room
Reward: Dvergan Chausses

Map fragment - Jawbone locations:
Given by Aubrey Gilcrest after collecting the previous treasure
Siren's Den, northernmost chest
Souldeep Fasting, past the first door opened during Until Death
Reward: Dvergan Cuirass

Map fragment - Cape Solace locations:
Given by Aubrey Gilcrest after collecting the previous treasure
Cliffbreak Fasting
Brigand's Hideaway (only available after finishing the quest The Exiles and starting The Invaders)
Reward: Dvergan Ceremonial Helm

After collecting all pieces of a given map it needs to be "used" from the inventory and a corresponding map marker is added which points to the treasure.

After all 4 treasures are dug up and the Fateless One speaks to Aubrey the quest will finish. However, this is not the end of the treasure hunt.

The final piece of the Dvergan Armor Set, and Aubrey's missing hand, can be found in The Jawbone area. Due north of the Mudhold Fasting there is a jump point leading to a big rock surrounded by shallow water and a few Boggarts. On the northern side of the rock there will be a Scuttlecrab. The Dvergan Gauntlets and Aubrey's hand can be found on its corpse.

Note: The crab won't appear until all 4 treasures are dug up and the Fateless One talks to Aubrey, thus finishing the quest. There is no use for the hand, no new dialogue options with Aubrey appear.