A bog or bogland is a wetland of soft, spongy ground that accumulates peat, a deposit of dead plant material—often mosses, and in a majority of cases, sphagnum moss. Broadly speaking there are raised bogs and blanket bogs.
Raised bogs are discreet, raised, dome-shaped masses of peat occupying former lakes or shallow depressions in the landscape. Their principal supply of water and nutrients is from rainfall and the substrate is acid peat soil, which can be up to twelve (12) metres deep. Raised bogs are characterised by low-growing, open vegetation dominated by mosses, sedges and heathers, all of which are adapted to waterlogged, acidic and exposed conditions.
Blanket bogs give the Irish landscape its unique appearance. We have two types of blanket bogs – Atlantic Blanket Bog and Mountain Blanket Bog. Atlantic blanket bogs cover the landscape of the west coast from sea level to an altitude of 200m. Here, rainfall is 1,200mm per year and the acid peat substrate ranges from 2 to 7m deep. Atlantic blanket bog vegetation has a characteristic grassy appearance due to the occurrence of purple moor grass (Molinia caerulea) and black bog rush (Schoenus nigricans). Patterned surfaces of pools, flat and sloped areas, flushes and swallow holes are important features of blanket bogs.
Mountain blanket bogs occur on relatively flat terrain in the mountain ranges above 200m altitude. Here rainfall is high and evaporation is low. Mountain blanket bogs are rain fed and their peat is acidic. The vegetation is characterised by the presence of ericoid shrubs and in particular ling heather (Calluna vulgaris), crowberry (Empetrum nigrum) and bilberry (Vaccinium myrtillus). Natural drains, lakes and flushes are features of mountain blanket bogs.