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 lower elevations in every direction. Due to the high winds, moderate precipitation and cool temperatures that generally prevail, conditions are favourable for formation of an acid bog, since water stagnates, but eventually evaporates with ensuing acidity enhancement of decaying organic matter. There was virtually no drainage outlet in prehistoric times, and little drainage even in modern times. Many coastal mosses were initiated by the process of glaciation, which sheared rock formations to a generally level terrain, while also gouging moderate sized craters that would pond. This description fits the fundamental situation of Portlethen Moss, where sphagnum would have flourished over