Bogs develop in areas of high rainfall where peat accumulates in areas that are poorly drained. The two main types are raised bog and blanket bog. Raised bogs are accumulations of deep peat in lake basins and they are largely confined to the midlands and mid-west. Upland blanket bog occurs on flat or gently sloping ground above 150 metres and is widespread on hills and mountains in Ireland. Peat depths are usually between 50 cm and two metres but much deeper accumulations can be found in places.
Wet heath is a similar habitat but tends to occur on the lower slopes of hills and mountains that are either too dry or too steep for deep peat accumulation and typically has an average depth of 15 to 50 cm. Both of these peatland habitats occur in the Nagle’s Mountains but intact sections are now rare as most areas have been planted with non-native conifers or drained and reclaimed for agriculture.