Portlethen Moss

Portlethen Moss is a raised acidic bog nature reserve on higher ground west of Portlethen town in Aberdeenshire. It sits at the edge of the Mounth, a coastal spur of the Grampian Mountains overlooking the North Sea. The site ranges from about 35 to 60 metres above sea level and contains rock outcrops left by the last Ice Age. No surface streams feed the bog; all water comes from rainfall that stagnates and turns acidic. The moss is one of many similar habitats in Aberdeenshire, including nearby Cookney Moss and Netherley Red Moss. The site carries layers of peat built up over millennia from decaying sphagnum moss and other plants. Generations of sedges and rushes grew on the floating mats, adding biomass and raising the bog’s surface. Heavy saturation could rupture the peat, spilling mud and debris into surrounding fields and expanding the moss. The water sometimes turned blood red from organic decay. Archaeologists have found Iron Age stone circles and artefacts nearby, showing early human use of the higher, drier ridges. Visitors walk among sphagnum hummocks, sedges and rushes that shelter insectivorous plants and butterfly larvae. Heath grasses provide food for roe deer. The raised stonework of the old Causey Mounth trackway still runs near the bog, linking the Bridge of Dee to Stonehaven. Remnants of Roman camps lie just south, where the army turned inland rather than cross the bogs. The Scottish Wildlife Trust monitors the habitat, though half the original moss has been lost to low-density housing since 1985.