Northumberland Trough and Solway Basin
C. N. Waters, M. T. Dean, N. S. Jones, I. D. Somerville, 2011. "Northumberland Trough and Solway Basin", A Revised Correlation of Carboniferous Rocks in the British Isles, C. N. Waters, I. D. Somerville, N. S. Jones, C. J. Cleal, J. D. Collinson, R. A. Waters, B. M. Besly, M. T. Dean, M. H. Stephenson, J. R. Davies, E. C. Freshney, D. I. Jackson, W. I. Mitchell, J. H. Powell, W. J. Barclay, M. A. E. Browne, B. E. Leveridge, S. L. Long, D. McLean
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Carboniferous rocks within this region occupy a broadly east-west trending graben, referred to as the Northumberland Trough within Northumberland (Bewcastle to the North Sea coast) and the Solway Basin in the vicinity of the Solway Firth, where much of the succession is obscured by Permo-Triassic strata (Fig. 40). The graben is bounded to the south by the Maryport-Stublick-Ninety Fathom Fault System, which forms the northern boundary of the Lake District and Alston blocks (see Chapter 12). The Carboniferous rocks are broadly separated from the Midland Valley of Scotland (Chapter 14), to the north, by the Lower Palaeozoic rocks of the Southern Uplands, which formed an emergent upland area throughout much of the Carboniferous, with local deposition within small basins. At the eastern onshore extent of the Southern Uplands a relatively condensed Carboniferous succession was deposited upon the Cheviot Block.
All of the regional stages of the Carboniferous are present at outcrop, though strata of Stephanian age have not been proved biostratigraphically. The oldest Tournaisian strata occur at outcrop along the northern margins of the Northumberland Trough-Solway Basin, represented by continental and peritidal deposits, typically separated by volcanic rocks (Inverclyde Group). These strata extend offshore in the North Sea (Chapter 15), linking directly with the outcrop of Inverclyde Group present within the Midland Valley of Scotland. In the Northumberland Trough-Solway Basin, the Inverclyde Group passes southwards into, and is overlain by, a lower to middle Visean heterolithic clastic and non-marine carbonate and fluvio-deltaic succession (Border Group).