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 saturated organic layers could actually rupture, spilling large volumes of mud and organic debris to surrounding fields, thus enabling a bed for further spatial expansion of the entire bog. Ultimately the colour of the moss waters became blood red in colour, from the successive organic decay and stagnation. Only in times associated with cattle grazing and significant human presence (probably the late Iron Age), would this process reverse and the bog reduce in size. A wide variety of sphagnum, sedges, rushes and other characteristic bog species inhabit Portlethen Moss. Sometimes insectivorous plants reside in mosses, since the soils are generally