“Medieval tile. Medieval pottery. Another piece of pottery. More tile. Animal bone.” Paul Gething, archaeologist, picked through his finds.

I had, literally, been walking on history, oblivious to its presence beneath my boots.

We were standing on a path down from the great crag of rock upon which Bamburgh Castle in Northumberland squats. Paul had just told me that most people are oblivious to what lies beneath their feet and I had challenged him to prove it. Within ten yards he’d found these remains.

Paul Gething is co-director of the Bamburgh Research Project (BRP), a multi-disciplinary archaeological dig investigating the history in and around Bamburgh. We’ve known each other for many years, but this was the first time I’d asked him to explain how he sees the world through the eyes of his discipline. I looked at his finds. To my eyes, they still looked like battered old stones.

“People have been here since Neolithic times, so it’s not hard to find things,” said Paul. “People drop litter now, and they threw away their rubbish then; we’ve not fundamentally changed over the centuries.”

In Northumberland, this continuity is visceral, tangible. The ramparts of Bamburgh Castle loomed above us. The fortress, capital of the lost kingdom of Northumbria, sits on top of a great outcrop of basalt, a part of the Great Whin Sill rock formation that stretches from the North Pennines to Northumberland. Out to sea, the Farne Islands, where St Cuthbert withdrew from the world and befriended the local eider ducks, are made of the same hard rock. The islands glittered darkly against an unexpectedly blue sky, while a few miles to the north, Holy Island (Lindisfarne) had, until the tide turned, rejoined the mainland.

Paul looked out to sea. “Ten thousand years ago, that was land. I think hunters camped here, watching the herds trailing past on their way to their feeding grounds.”We’d started the day by inspecting the trenches the BRP has dug in the grounds of the castle. Teams of archaeologists on hands and knees were carefully scraping away the earth with trowels, noting and tagging every find. For the really delicate work, they employed toothbrushes. The archaeologists here come in all ages, from pensioner to schoolchild, for one of the key objectives of the Bamburgh Research Project is to make archaeology accessible: anyone, from members of the public to Indiana Jones, can dig after being taught the necessary skills. The site is open in the summer and people can sign up for anywhere between one day and two weeks.

Leaving the archaeologists in the trenches, we set off along a section of the St Oswald’s Way long distance path. It seemed to me that Bamburgh Castle, once the capital of the kingdom of Northumbria, was an obvious place to do archaeology, but Paul bet me that archaeology could illuminate any walk.

“Before setting out, look at the map. The names are clues to the past. For instance, -burgh is the Anglo-Saxon word for ‘fort’, and -by is Old Norse for a village, so that tells you who settled there and named the features of the landscape. Then look at aerial photographs, or satellite images – Google makes this easy – since things often show up more clearly from above.”

Heading down into the marram grass covered dunes, Paul told me how an old Ordnance Survey map had given them a vital clue when the BRP first started digging here. There were written references to a burial ground in the vicinity of Bamburgh Castle, but they had no idea where to search for it. But then they looked at the very first Ordnance Survey map of the area and there, to the south, were the neatly printed words ‘Danish burial ground’. We made our way through a small wood (“Just regrowth, only a couple of hundred years old”), the air thick with the buzzing of heat-drugged insects, until we came to the burial ground. Paul said they’d found over 100 skeletons here, dating from the seventh and eighth centuries. The remains indicated the people buried here were from the nobility – “They were all well fed” – and some had come from as far away as Western Scotland and Norway, only to meet their end in the service of the kings of Northumbria.

Heading inland, Paul stopped at a pasture. The cows looked up placidly before returning to cropping the grass.

“Ridge and furrow,” Paul said, indicating the undulations that ran across the field. “Or rig and frig in archaeological slang. Medieval, judging by the distance between the ridges. Roman fields have narrower gaps.” Parallel lines, like the ripples that form on beaches as the tide goes out, marked the field in straight lines. In medieval times common land was ploughed or dug in long parallel strips. The soil from the furrow was piled on to the ridge, creating two different microclimates for crops. In a dry season, the seeds down in the water-collecting furrow would be assured enough moisture for growth, but if the year was wet, the crops in the freely-draining ridge would flourish. Thus medieval peasants hedged their bets and their labour to ensure a crop. Where the field has been turned over to pasture rather than cross ploughed, the centuries-old pattern of cultivation can still be clearly visible.

“The rule of thumb is the wider the gap, the nearer it is to our own time. Roman fields have a three-metre gap between the ridges, medieval ones from five to eight metres.”

Paul was winning the argument before we’d gone a mile. I asked him if there were any other archaeological landscape features that an amateur could spot and he pointed to a roughly circular patch of nettles sitting alone in the corner of a nearby field. Nettles love phosphorus, and the excrement of cattle and sheep is rich in the element. Those solitary patches I’d often seen in the past usually marked the site of a medieval sheep or cow pen. Although the enclosure had disappeared, the plants lived on on the bounty left by the long-dead animals.

“My family are always moaning that whenever we go anywhere, I’m always saying that’s rig and frig, or there must have been Roman villa in the vicinity, but I can’t help it. It’s just part of the way I automatically process a landscape. For instance, near where I live in York, a Second World War airfield is reverting to scrub. It’s an archaeological test bed. There’s rig and frig fields, crab apples that aren’t native to Britain – my guess is that pilots flew over from America, ate the apple they’d bought there and then threw away the core – and miles of underground tunnels that I’ll bet future archaeologists will take to be sewers, but are actually communication ducts.”

A couple of miles inland, with the Cheviots looming in the distance, we arrived at another BRP dig. This one cut through the grass, topsoil and subsoil to reveal the limits of a prehistoric lake. One of the archaeologists there told me that in Mesolithic times, that is between 10,000 and 5,000 years ago, where we were standing was a large figure-eight-shaped lake, and we were standing at the pinch point of the lake. It was the obvious place for a settlement, but our distant ancestors were proving elusive. The archaeologists had only uncovered the remains of a millennia-old ditch so far.

Walking back to the castle, Paul showed me an arrowhead he’d found at the edge of a field. It was an exquisitely worked, barbed and tanged late Neolithic flint. But what could this solitary find tell us?

“I’m firmly convinced that the key skill archaeologists have to learn is how not to focus on what is in front of them. Five thousand years ago, skilled artisan could produce half a dozen arrowheads like this every hour. They were as disposable as Bic razors. The shafts, on the other hand, were a different matter. Finding and preparing a truly straight length of wood was difficult. Once that was done, the shaft had to be fletched too. For Neolithic man, the valuable part of an arrow was not the arrowhead but the shaft. What would happen, though, if an animal wasn’t killed outright but fled, taking your valuable arrow with it? So they made their arrows in such a way that the arrowhead would break off easily, leaving the shaft to be retrieved.”

Looking at the killing instrument, I was transported back in time to a world of woods and marshes, and a hunter drawing his bow on a deer and loosing his arrow, but the beast, startled, leapt away, the arrow protruding from its haunch. The shaft broke off as the deer careered through the trees and the pursuing hunter spotted the bright feathers of its fletch lying in the moss. The deer escaped, only to die a few days later when the wound became infected. Scavengers cleared the remains, but the indigestible flint of the arrowhead fell to the earth, and was covered over, only to be uncovered centuries later when a sweating medieval peasant piled the spoil from the furrow on to the adjacent ridge. There it remained, alternately exposed and hidden, until a passing archaeologist saw it glittering on the ground and grasped its significance.

Paul had won the bet.