"The Gweebarra estuary marks the end of a rift called the Great Rift formed during the Ice-Age andrunning south east to north west to the source of the river at Lough Barra. The Great Rift continues north westwards from Lough Barra along the Owencarrow river to Glen Lough in the north west of Donegal and can next be seen joining up with rift along which the Caledonian Canal runs dividing Scotland in two. This Great Rift lays claim to being the oldest scar on the face of the earth. It can be seen more clearly on a larger map taking in both Scotland and Ireland. It is suggested that North West Donegal may have moved as much as 25 miles to the south east in relation to the rest of the county on the southern side of the Lennan Fault."