Walking in the North Pennines. Paddy Dillon

Kirkby Stephen, Appleby and Brampton. While all those places lie outside the boundary, each could be considered a ‘gateway’ to the North Pennines. The largest town inside the AONB is Alston, but Stanhope and Middleton-in-Teesdale are only just outside the boundary.

      The AONB includes all the high ground and most of the dales, though half of Teesdale and Weardale are excluded, along with the large forests at Hamsterley and Slaley. Some land south of the busy A66, which was never claimed by the Yorkshire Dales National Park, has been included in the North Pennines. The counties of Cumbria, Durham and Northumberland each claim a third share of the North Pennines, and an office administering the AONB has been established at Stanhope.

      The North Pennines was once the world’s greatest producer of lead, providing everything from roofing material for churches to lead shot for warfare. A considerable quantity of silver was also mined. The broad, bleak and boggy heather moorlands have long been managed for the sport of grouse shooting, and are best seen when flushed purple in high summer. For many years, walkers wanting to reach the most remote and untrodden parts of the North Pennines might have been put off because of the lack of rights of way, but the recent Countryside and Rights of Way Act 2000 has resulted in vast areas being designated ‘access land’.

      There has probably never been a better time to explore the North Pennines and this guidebook contains detailed descriptions of 50 one-day walks. These cover nearly 800km (500 miles) of rich and varied terrain, serving to illustrate the region’s history, heritage, countryside and natural wonders. This terrain ranges from field paths and old railway tracks to open moorlands on the high Pennines. You will be able to discover the region’s geology, natural history and heritage by following informative trails, or taking in specific sites of interest along the way. A network of tourist information centres can help you discover the best places to stay, how to get around and what to see.

Geology

      The geology of the North Pennines can be presented in a fairly simple manner, but can also become extremely complex in some areas. The North Pennines was designated the first ‘Geopark’ in Britain in 2003, in recognition of how its geology and mineral wealth have shaped the region. The oldest known bedrock is seldom seen at the surface, but is notable along the East Fellside. Ancient Ordovician rock, comprising mudstones and volcanics, features on most of the little hills between the Vale of Eden and the high Pennines, but being heavily faulted, tilted and contorted, is very difficult to understand, even for students of geology. Ordovician rock is about 450 million years old and lies beneath the whole of the North Pennines. There is also a significant granite mass, known as the Weardale Granite, which outcrops nowhere, but was ‘proved’ at a borehole drilled at Rookhope.

      Late-flowering hayfields can be enjoyed in Upper Teesdale and Upper Weardale (Walk 28)

      Looking back to the Carboniferous period, 350 million years ago, the whole area was covered by a warm, shallow tropical sea. Countless billions of shelled, soft-bodied creatures lived and died in this sea. Coral reefs grew, and even microscopic organisms sometimes had a type of hard external or internal structure. Over the aeons, these creatures left their hard shells in heaps on the seabed, and these deposits became the massive grey limestone seen on the fellsides and flanks of the dales today. A dark, durable, fossiliferous limestone outcropping in Weardale is known as Frosterley Marble. Even though it is not a true marble, it polishes well and exhibits remarkable cross sections of fossils.

      Even while thick beds of limestone were being laid down, distant mountain ranges, being worn away by storms and vast rivers, brought mud, sand and gravel down into the sea. These murky deposits cut down the light in the water and caused delicate coral reefs and other creatures to die. As more mud and sand were washed into the sea, a vast delta system spread across the region.

      Frosterley Marble

      At times, shoals of sand and gravel stood above the waterline, and these became colonised by strange, fern-like trees. The level of water in the rivers and sea was in a state of fluctuation, and sometimes the forested delta would be completely flooded, so that plants would be buried under more sand and gravel. The compressed plant material within the beds of sand and mud became thin bands of coal, known as the Coal Measures. This alternating series of sandstones and mudstones, with occasional seams of coal, can be seen all the way across the region. The various hard and soft layers can often be detected where the hill slopes have a vaguely stepped appearance today.

      Other geological processes were more violent, resulting in the fracturing and tilting of these ordered sedimentary deposits. The whole series is tilted so that the highest parts of the Pennines are to the west, diminishing in height as they extend east. Far away from the North Pennines, there were violent volcanic episodes, and at one stage a sheet of molten rock was squeezed between existing layers of rock, solidifying as the ‘Whin Sill’. Deep-seated heat and pressure brought streams of super-heated, mineral-rich liquids and vapours into cracks and joints in the rocks. These condensed to form veins of mixed minerals, which included lead, silver and copper. Associated minerals are barytes, quartz, fluorspar, calcite, and a host of other compounds. Coal mines and stone quarries are found throughout the North Pennines, and the region was once the world’s greatest producer of lead.

      Most of the rock seen by visitors around the North Pennines is Carboniferous. Younger rocks are found outside the region, such as the New Red Sandstone in the Vale of Eden, formed in desert conditions, and the soft Magnesian Limestone in the lower parts of County Durham, formed in a rapidly shrinking sea beside the desert. Apart from being lifted to great heights, the only other notable geological occurrence in the North Pennines was during the last ice age, when the whole region was buried beneath a thick ice sheet for about two million years, completely freeing itself from such conditions only 10,000 years ago.

      Walkers who wish to delve more deeply into the geology of the North Pennines could equip themselves with specialised geological maps and textbooks, or explore the region in the company of knowledgeable experts. The North Pennines was designated as a UNESCO Global Geopark in 2015. Look out for ‘Geopark’ leaflets describing geological trails and curiosities. From time to time, guided walks are offered that feature geology, as well as visits to mines.

      THE WHIN SILL

      Many dramatic landforms around the North Pennines and beyond owe their existence to the Whin Sill. This enormous sheet of dolerite was forced into the limestone bedrock under immense pressure in a molten state around 295 million years ago. As the heat dissipated, the limestone in contact with the dolerite baked until its structure altered, forming the peculiar crystalline ‘sugar limestone’ which breaks down into a soil preferred by many of Teesdale’s wild flowers.

      While weathering, the Whin Sill proves more resistant than the limestone, forming dramatic cliffs such as Holwick Scars, Cronkley Scar and Falcon Clints. Where the Whin Sill occurs in the bed of the Tees, its abrupt step creates splendid waterfalls such as Low Force, High Force, Bleabeck Force and Cauldron Snout.

      The rock has been quarried throughout this part of Teesdale, generally being crushed and used as durable roadstone. It outcrops from time to time along the East Fellside, most notably at High Cup, where it forms impressive cliffs. Outside the North Pennines, the Whin Sill is prominent as a rugged ridge carrying the highest stretches of Hadrian’s Wall, and it features regularly as low cliffs along the Northumberland coast, including the Farne Islands.

      The River Tees displays some of the finest and most powerful waterfalls in England (Walk 25)

Landscape

      Many visitors are drawn to the North Pennines to enjoy its extensive and apparently endless moorlands, while others are content to explore the gentler green dales. The scenery is remarkably varied, but the sheer scale of the open moorlands is amazing. Almost 30 per cent of England’s blanket bog is in the North Pennines. It is worth bearing in mind that the moors are entirely man-managed,