An ambitious campaign to get a huge swathe of Kent granted Unesco status is to be kick-started later this year.

It wants to become the world's only chalk-based Global Geopark – covering around a quarter of the county, before stretching under the Channel and into northern France.

The chalk ridge under the sea is all that's left after a catastrophic flood thousands of years ago swept the land between Dover and Calais away, carving out the famous White Cliffs of Dover and cutting us off from the Continent.

Geologists believe the chalk bridge which once connected England with our continental neighbours – and separating the English Channel with the North Sea – started to be worn away by water almost half a million years ago.

Hundreds of thousands of years later, it was then ruptured, making our nation an island.

Now a campaign will launch in the autumn, spearheaded by the Kent Downs AONB (Area of Outstanding Natural Beauty) and counterparts in France – the Parc Naturel Régional des Caps et Marais d'Opale – to have the area recognised, and thus protected, by Unesco.

If successful, the Cross-Channel Geopark, as it would be known, would be the first of its kind to be awarded Unesco status and the only Geopark to be shared by two countries that don't share a land border.

Unesco – the United Nations Educational, Scientific and Cultural Organisation – recognises and supports areas of "cultural and natural heritage around the world considered to be of outstanding value to humanity".

Best known for its World Heritage Sites, which recognise and protect man-made structures, its Global Geoparks are described as "single, unified geographical areas where sites and landscapes of international geological significance are managed with a holistic concept of protection, education and sustainable development".

The North-West Highlands, Anglesey and North Pennines and examples of the seven existing Unesco Geoparks in the UK.

The site in Kent bidding for the Unesco status would cover the entire Kent Downs Area of Outstanding Natural Beauty, stretching from Sevenoaks, right through the Kent Downs and across the Dover Strait to France, into Saint-Omer, 25 miles inland. A total distance, as the crow flies, of around 110 miles.

Key to the bid is if granted Unesco status, it will be prove a huge boost to tourism efforts by giving it global recognition.

Kent Downs AONB director Nick Johannsen explained: "We know this is a truly unique and wonderful landscape.

"Securing the Kent Downs as part of a larger Global Geopark is a step up and an even greater opportunity for the landscape to be recognised and celebrated and to support a sustainable visitor economy.

"We really want to help people discover or re-discover the landscape, to love it, feel proud of it and ultimately help us to protect it too.

"If you care about something, you champion it and that's what we'd like to encourage people to do."

It is urging locals, landowners and businesses to fill in a survey – click here to access – to help inform the bid.

Deirdre Wells, CEO of the county's tourism champions Visit Kent, added: "Securing the status for this unique part of Kent's landscape will be critical not only to attracting international visitors but supporting a real pride in place for our local communities.

"Kent has some ambitious plans to become a leading sustainable destination.

"We want to encourage visitors from near and far to enjoy the breadth of all that Kent has to offer – from its beautiful countryside to its world-class heritage and locally sourced produce – but to do so in a way which protects our landscape, nurtures our environment and offers engaging experiences which will keep people coming back again and again."

Only one bid from any one nation can be made for the status each year – meaning both the UK and France have agreed to support the bid.

While AONBs already enjoy development protection, gaining the status would provide no further protections or additional access to land on the area included in the bid.

The campaign will be funded by the Kent Downs AONB – which is funded both by local authorities and receives EU Interreg funding. No additional funds from local authorities will be required for the bid process.

The project has been a work in progress since last year and organisers say they are working closely with Unesco to ensure the bid ticks the right boxes.

Roger Gough (Con), leader of Kent County Council, said the authority was backing the bid. He said: "Kent is full of heritage, usually associated with the buildings. We’re very well known for our castles, but what about our chalk?

“You can’t miss the White Cliffs as you approach from the Channel but chalk also connects us to France and shapes much of our landscape on both sides of the water. It has a huge impact on how we live and use the land.

“It’s a very exciting and ambitious bid which will bring massive rewards and push sustainable tourism – which is brilliant to see.”

The campaign will launch with a free festival in Folkestone over September 23-25.

Working with Folkestone Fringe and Creative Folkestone to put on the arts-led festival, it will expand on the established SALT Festival of the Sea and Environment.

Offering guided walks, community meals, photography and much more, it will celebrate the landscape which would form part of the bid. More details are set to be released in the coming weeks.

Nick Johannsen of Kent Downs AONB added: "It is the communities, landowners and land managers, businesses public bodies and local charities who know their areas best, and we are asking them to tell us what they love about their places, to share with others and with Unesco.

"This will be an essential element of securing Unesco status and making the Geopark a success."

James Bridge, secretary-general of the UK national commission for Unesco, said: “There are many extraordinary Global Geoparks around the world and this would be not only the first ever chalk-based Global Geopark, but also the only cross border Geopark not connected by a land boundary.

"We are excited to see territories in England and France collaborating towards a shared Unesco ambition.”

The application for the Unesco status will be submitted in November 2024 – with a decision expected in the spring of 2026.