Head to Portsalon is a band of Quartzite. Knockalla Mountain is also formed of Quartzite. The landscape of Fanad has been shaped by geological processes which include the effects of periodic covering with ice sheets and glaciers as recently as 14,000 years ago. The retreat of the ice sheet had a major impact on Fanad and surrounding areas. It is speculated that much of Lough Swilly was may have been dry land which was flooded due to a rise in sea level within the last 10,000 years. Mulroy Bay may have been similarly formed at this time. The peat outcrops on the foreshore at White Strand north of Rathmullan contain the remainder of trees which were submerged by the advance of the sea in this area. Many of the beaches on the Fanad shoreline were formed at this time by glacial deposits which were subsequently reworked by the actions of waves and currents. In common with much of the rest of Ireland, the post-glacial landscape gradually changed with rises in temperature from open tundra to one dominated by forests of pine, oak, alder, hazel and birch, with breaks in the canopy on the edges of the intervening expanses of lake and bog. This was probably the landscape which greeted the earliest settlers who ventured along the coastline in the late Mesolithic Period, possibly about 5,000 BC. There is archaeological evidence of human occupation of coastal areas of Inishowen at Dunaff and west of Horn Head during this period and it is reasonable to assume that Fanad also saw some transient occupation at this time. The subsequent evolution of the landscape in Fanad probably owes more to human intervention than to natural forces, reflecting the shift from visits by Mesolithic hunters, fishers and gatherers to the introduction of primitive farming during the Neolithic period from 4,000 BC onwards. The tree-covered landscape of the Mesolithic period would have given way gradually to a more open countryside in arable areas, marking the beginning of the contemporary landscape of Fanad, with its mixture of arable land at lower levels, with scrub and gorse covered uplands, and bogs interspersed with occasional lakes and streams. History Mesolithic and Neolithic periods There is no specific evidence of human occupation of Fanad during the Mesolithic period (8,000–4,000 BC) though as noted already, it is reasonable to assume that there was some temporary occupation of coastal locations during this