The Pattern of Deglaciation in Part of North Northumberland

Abstract

Landforms of meltwater erosion and deposition in north Northumberland indicate that the deglaciation of the area can be resolved into four consecutive phases: (i) a period of ice-directed meltwater drainage; (ii) a period when confluent ice masses parted, resulting in the development of proglacial lakes fed by ice-directed meltwater streams; (iii) a period when meltwater and streams from ice-free ground were able to flow freely down-slope beneath stagnant ice; (iv) a period when a large lake was impounded on the margin of the dwindling Tweed ice mass and when streams in Northumberland had become more or less established in the valleys they presently occupy. THE eastern flanks of the Cheviot massif rise steeply from fringing lowlands to the plateau summit of The Cheviot at an altitude of 816 m. Composed predominantly of andesitic lavas of Old Red Sandstone age, with an emplacement granite in the centre, the massif is deeply dissected by a near-radial system of narrow, steep-sided valleys. Basins and cuestas underlain by rocks of Carboniferous age curve gently round the eastern perimeter of the massif. Rising to altitudes of 150 m, 250 m and 300 m, the cuestas are arranged crescentically and en echelon, presenting steep, west-facing escarpments of saidstone to the massif. The basins are of cementstone, and, lying mostly below ioo m, they are contained between cuestas and between cuestas and the massif. The basin and cuesta relief considerably influenced the pattern of deglaciation in north Northumberland.