As a sparsely-populated upland region known for its moorland ecology and industrial archaeology, a large part of the North Pennines is protected as a National Landscape and a UNESCO Global Geopark.

The North Pennines are formed from a succession largely of sedimentary rocks laid down during the Palaeozoic era, later intruded by the Whin Sill and affected by glaciation during the Quaternary period.

Mud and volcanic ash deposited during the Ordovician and Silurian periods were buried and subsequently faulted and folded during the Caledonian orogeny, the mudstone becoming slaty.

These rocks which are between 500 and 420 million years old are now exposed along the great scarp which defines the western edge of the area and also in an inlier in upper Teesdale.

Repeated cycles of inundation led to the development of a series of cyclothems; the laying down of layers of limestone, shale and sandstone with occasional coal seams.

Shortly afterwards, (c. 295 million years ago) molten rock once again intruded the sedimentary succession, this time resulting in the emplacement of the doleritic Whin Sill within the Carboniferous sequence.

During the rest of this period and into the Triassic at the start of the Mesozoic era, desert sands characterised the area; these are now seen as the New Red Sandstone of the Vale of Eden, the eastern parts of which form the lower slopes of the Pennine scarp and are within the AONB.

There is no bedrock of younger age to be found within the North Pennines; for much of the time since the deposition of the Triassic sandstones, it is likely the area was above sea level and subject to erosion.

[16] The landscape of the North Pennines AONB is one of open heather moors between deep dales, upland rivers, hay meadows and stone-built villages, some of which contain the legacies of a mining and industrial past.

There is a small National Landscape visitor centre at Bowlees which aims to provide a gateway to Upper Teesdale and the wider North Pennines.