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It looks like a long way to the prehistoric dig site, and there’s a lot of slippery mud separating me from it. But I have more to worry about than face-planting into the estuary. “We actually need to give you the safety talk,” says , an archaeologist with the Museum of London Archaeology.

As we stand in a battering wind looking out at the muddy beach at Cleethorpes in Lincolnshire, he tells me there are at least three ways to get killed here: walking on an unexploded bomb, stepping into quicksand, or ignoring the tide timetable. The sea sweeps in behind the dig, cutting off anyone foolhardy enough to venture out at the wrong moment.

So why are we here? Well, coastal archaeology has an urgency you get nowhere else. The sea reveals whatever our ancestors left in the mud with no warning. And then, just as quickly, it can wash them away forever.

That’s why the Museum of London Archaeology began its , which trains ordinary people to keep an eye out for interesting finds and record them. It gives us a better chance of catching the fleeting artefacts that are key to understanding our ancient past.

The project’s of humans and animals, like some found near Liverpool from an extinct species of huge cow called an auroch; Britain’s first lifeboat station, built in Formby probably in 1771, and a 40-metre-deep .

Stuck in the mud

Sherman and his colleague Megan Clement, based in York, train people in the north of England and act as a response team when something interesting crops up – as it did here on the outer reaches of Cleethorpes seafront.

I put on two fleeces, a coat, two pairs of socks and wellington boots and stick tight behind Clement and Sherman as they pick their way in a meandering trudge through the shin-deep mud.

The residents of Cleethorpes knew there was something out here – the strange black objects that I can now see sticking out of the mud were a giveaway. When Clement and Sherman got wind of the rumours last spring, they went to investigate.

“It was freezing but packed,” says Clement. “Typical British people on the beach despite the cold. We got the last parking space.”

They found the black shapes were tree trunks from a 4300-year-old forest. But there was more: running straight through the forest was a path that shouldn’t be there.

Prehistoric boardwalk

That is, if you subscribe to the conventional idea that Stone Age people were uncultured nomads, eking out a subsistence living in the wild.

It’s clear that is not the case – witness Stonehenge, for instance. But it’s hard to counter this view with evidence, Sherman says, because Neolithic people had an oral tradition and left behind few artefacts.

That makes the trackway a valuable discovery. “This is the best thing we’ve found,” says Clement of the CITiZAN project. It’s not much to look at. Just a few metres of rough strips of intensely black wood, cresting out of the peat.

But the strips have been arranged carefully, a bit like a wooden boardwalk. Sherman sees it as evidence that the Neolithic people who made it were organised. “This isn’t just a path, it’s a wide track, which means they were taking the time to grow the wood and maintain it. It would have been a lot of effort,” he says.

Sherman and Clement think this section of the trackway will be washed away by tides within two years. But as the peat is eroded further, more of the track should be revealed.

As I stand there with the mud squelching over my wellingtons, I wonder if we’ll eventually be able to work out where it went. During the Stone Age, this section of land would have been nowhere near the coast. So where were the ancient Britons going on this path? I bend down and follow the scraps of wood for a few metres to the south, but they disappear beneath the mud.

Tomorrow Sherman and Clement will be taking a group of local volunteers to document the site more carefully. Armed with handheld GPS receivers, they can record the precise positions of the track and the trees.

You can tell a lot from this, says Sherman. For instance, by checking if the trees are more widely dispersed than they would be naturally, you can work if the forest was maintained. That would provide more valuable evidence of Neolithic organisation, without the need to excavate the trees and check for characteristic cut marks.

We’ve almost left the site when Sherman freezes – he’s spotted something in the water. After a few careful photographs, he plucks it out. It’s a worked wooden stake. Who knows what it was used to peg down. We could so easily have missed it – the sea probably dislodged it from the peat during the previous high tide and in a few hours it would have been lost to the sea forever.

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