The geology of Northumberland National Park in northeast England includes a mix of sedimentary, intrusive and extrusive igneous rocks from the Palaeozoic and Cenozoic eras.
The geology of the rest of the national park is characterised largely by a thick sequence of sedimentary rocks of Carboniferous age.
[1] The exploitation of various of these rocks and deposits has contributed to economic activity in the area and left a number of legacies in the landscape.
Various archaeological and historical sites are associated with the geological landscape, not least Hadrian's Wall built in large part by the Romans along the outcrop of the Whin Sill.
An upstanding Cheviot Block and an upstanding Alston Block were separated by the Solway-Basin – Northumberland Trough Greywackes originating during the Wenlock epoch (428 – 422 Ma bp) of the Silurian Period are assigned to the Riccarton Group and occupy an area either side of the border with Scotland to the north of Byrness.
The Tyne Limestone occupies a large area around Otterburn, Bellingham and Kielder Reservoir extending west to the Cumbrian border.
The overlying Alston Formation extends south from the Scottish border along the coastal strip before turning inland through Alnwick towards Greenhead.
The quartz-dolerite was emplaced within lower Carboniferous bedrock in a sheet which extends south and east fromjust within the southern margin of the park.
The dyke which occasionally achieves a width of 30m emanates from a source in the Mull igneous centre in the west of Scotland.
There are also a number of areas of glacio-fluvial sands and gravels representing glacially derived material re-worked by rivers.
The Pennine tills are generally dark grey reflecting the nature of the Carboniferous bedrock from which they largely originate.