Faddan More Psalter used as a liner to stiffen the cover somewhat. Low oxygen levels in the bog provide unusual preservation conditions, and bogs were often used by Irish monks as hiding places for valuables in the face of Viking raids. In addition to low oxygen levels, sphagnum moss, of which the peat bog is composed, produces an antibiotic substance called sphagnan that binds with proteins on the surface of microorganisms, immobilising them. Its highly reactive carbonyl groups can alter chemicals and nutrients that would otherwise decompose organic matter. And above all the sphagnum moss causes organic material to undergo chemical changes itself
Portlethen Moss have been enhanced by proximity to the sea and natural defensive protection of the moss to impede intruders. From Tacitus accounts of the Roman general Agricola, it is known that the Romans were daunted by Portlethen Moss, Netherley Red Moss, Cookney Moss and other local bogs that hindered travel. This is also evidenced by the Roman Camp of Raedykes having been established immediately south of this cluster of mosses; the Romans not being able to progress further north, turned inland toward Netherley.The Portlethen Moss is near the Grampian Mountains. The ancient Causey Mounth passage specifically connected the Bridge of Dee