Risley Moss peat accumulation filled the depression, allowing colonisation by bog mosses such as the "Sphagnum" varieties, thus giving rise to the name "moss". Risley Moss is one of only two mosses in Cheshire where the water level has been deliberately raised in an attempt to encourage the regeneration of an active bog surface. The long-term restoration project to re-wet the moss began in 1978 and was completed in 2002. This scheme was undertaken to create a series of scrapes and bunds to retain water and recreate the perfect conditions for bog flora such as cotton grass and sphagnum mosses to re-colonise
Portlethen Moss have been enhanced by proximity to the sea and natural defensive protection of the moss to impede intruders. From Tacitus accounts of the Roman general Agricola, it is known that the Romans were daunted by Portlethen Moss, Netherley Red Moss, Cookney Moss and other local bogs that hindered travel. This is also evidenced by the Roman Camp of Raedykes having been established immediately south of this cluster of mosses; the Romans not being able to progress further north, turned inland toward Netherley.The Portlethen Moss is near the Grampian Mountains. The ancient Causey Mounth passage specifically connected the Bridge of Dee