The Mertis Spiral has no economy, as there are no settlements in the Spiral and no natural resources either.
The Mertis Spiral is a series of twisting, icy tunnels east of Mertis, south of Silvar, and north of the Tower Colony, in Honeycomb Province of the Kingdom of Avernum. There are no settlements in the Spiral itself, only Mertis west of the Spiral.
The history of the Mertis Spiral is categorized into two Plagues caused by the death of members of the First Expedition. These plagues consist of sending swarms of undead towards the unwisely placed settlement, Mertis.
When the Empire found the caves of Exile, they first sent down the First Expedition, to determine its worth as part of the Empire. Very early on, the Expedition split into several groups for unknown reasons. One particular group was pursued by hostile Slithzerikai, and fought a running battle into the Mertis Spiral. Despairing, a magic barrier was erected by a mage to prevent the Sliths from getting to them. However, the group was unable to dispel the barrier, and starved to death. Their spirits haunted the Mertis Spiral for many years.
First Mertis Plague
After the Founding of Avernum, Mertis was soon established unknowingly near this cursed area. Soon, hordes of undead started wandering into the city, and the guards had difficulty keeping them out. The Avernite Army did little to help, due to their fighting in the First Slith War, but eventually Hawthorne's Assassins infiltrated the Mertis Spiral, and killed many of the undead. Eventually, they found the cause of the problem, and not being particularily powerful in terms of priestly powers, they could do nothing to stop it.
Second Mertis Plague
When the Empire-Avernum War started up, the undead rose again. The village continued suffering silently, until the Empire War Heroes came to the Mertis Spiral. Like the other adventurers before them, they infiltrated through, and eventually saw the scene of death. This group of adventurers however, was stronger, and successfully cleansed the curse by using the Ritual of Sanctification.