RILEY BROOK, New Brunswick – Whether nature knows no boundaries or la nature ne connait pas des frontiers, the people who hike the International Appalachian Trail from the peak of Mount Katahdin to the tip of Newfoundland have little use for geopolitical borders, international politics or language barriers. The mountains are all that matter.

About 30 people from throughout the northern Appalachians gathered Saturday in New Brunswick to celebrate the trail’s first decade with a soggy hike up Mount Carleton, the Maritime Provinces’ highest peak.

The crowd included retirees who have logged hundreds of hiking miles, schoolchildren making their first climb, a monolingual American and his French-speaking wife who met while hiking and fell in love over a two-way dictionary, and the trail’s “chief promoter and ambassador,'” Dick Anderson of Freeport, Maine.

The idea for the trail struck Anderson while he drove over the rolling hills of northern Maine’s Appalachians. We all share the same mountains, the same French and British colonial heritage, he thought.

Why should the trail have to stop just because an artificial line has been drawn across the continent?

Ten years later, that dream has grown into a hilly, 1,300-mile trek.

“The idea was to get people to think North … to think about being in this corner of the Earth with the Appalachians going through, and not about boundaries,” Anderson said.

Today, the trail includes 100 miles in Maine, beginning where the Appalachian Trail ends atop Mount Katahdin, and winding its way through the forests of northern Penobscot County and the highlands of Aroostook. After riding the international border for 11 miles, the trail crosses into Canada and continues through 170 miles of New Brunswick, 417 miles of Quebec, and, the most recent addition, nearly 600 miles of Canada’s easternmost province, Newfoundland and Labrador.

The federally owned Appalachian Trail, 2,842 miles between Georgia and Mount Katahdin, draws hundreds of “through-hikers” every year. Increasingly, they’re continuing on to the cooperative International Appalachian Trail. Already 11 people have hiked the full route, and thousands have trekked a mile or two somewhere along the trail.

“It’s a natural next step,” said Fred Kirch, who splits his time between Delaware and the Gaspe Peninsula in Quebec. Kirch hiked the Appalachian Trail several years ago and is anticipating the AIT as his next challenge.

“You get finished [with the AT] and say, ‘What am I going to do now? Oh, keep on going … I’ve never hiked on a trail that the farther I walk, the farther I am behind,” he joked.

The trail started with an Earth Day 1994 campaign promise to extend the Appalachian Trail by then-gubernatorial candidate (and Anderson’s employer) Joseph Brennan. Critics called the idea “political grandstanding”; the Appalachian Trail Conference gave a resounding no; and Brennan lost the election. But Anderson never lost his enthusiasm, drawing support from people such as Don Hudson of Arrowsic, Maine, and Viateur and Josclyn DeChamplain of Matane, Quebec, who climbed Mount Carleton together 10 years ago with a dream of connecting the region’s three highest peaks, Katahdin, Carleton and Mont Jacques Cartier, in Quebec.

The trail has succeeded because each local chapter operates independently, establishing its trails and facing its unique challenges.

“It hasn’t been easy in the state of Maine,” Hudson said. “For years and years, it had been difficult for us to get permission from landowners to put the trail through the woods.”

Land in northern Maine has swapped hands constantly during the past decade, and many buyers, spooked by stories of view easements and challenges to developments near the Appalachian Trail in western Maine, were hesitant to invite hikers into their forests. Instead, the Maine chapter laid its trail alongside country roads.

Maine’s effort has been entirely volunteer-based, though the Baldacci administration has been more supportive of the effort than former Gov. Angus King, Hudson said.

In fact, Gov. John Baldacci sent a note of congratulations to Saturday’s event.

“In this period of globalization, we must think beyond borders,” Baldacci wrote. “[The trail] serves as a reminder that the mountains and the rivers and the forests are our real heritage … they will outlast us all.”

Behind the scenes, Baldacci and the state Department of Conservation have been working to find a better route for the trail – purchasing an old railroad bed in Aroostook County and looking into the possibility of routing the trail over Daicey Mountain in Baxter State Park, said Hudson.

“We’re still looking for a less dusty path between Baxter and the border,” he said.

Meanwhile, New Brunswick and Quebec built connections through their systems of provincial park trails, and the AIT, which is known as the Sentier International des Appalaches in French, had its first through-hiker three years later.

Quebec, which until a recent change in government had full provincial support to spend millions on trail development and promotion, boasts trailside log cabins and “five-star privies” as well as the trail’s longest leg, from the New Brunswick border to the tip of the Gaspe Peninsula.

Volunteers in Newfoundland and Labrador, on the other hand, are just getting started. Two years ago, a group of hikers decided to create a trail leg, which it estimated will stretch for 600 miles along cobble beaches and through bogs once it’s completed, although a few intrepid hikers already have forged their own trails to make the journey.

“There are small bits and pieces and sections,” said Clarence Pelley of Stephenville, Newfoundland, showing slides of the caribou, whales and even occasional icebergs visible from the new route.

Now, the trail’s founders are looking even farther afield.

The Appalachians were formed about 220 million years ago, when the Earth’s continents were joined like pieces of a jigsaw puzzle in the ancient supercontinent that geologists know as Pangaea.

Bits of the Earth’s crust, known as plates, float atop its liquid rock inner layers, carrying the continents to and fro over millennia, to form land masses.

Once Pangaea was formed, the plates continued to drift inward, shoving the land upward over millions of years – a blink of the eye in geologic time – giving birth to a towering new mountain range. The same principle is at work today, helping the Himalayas to grow a fraction higher every year.

When the plates receded about 165 million years ago, slivers of the Appalachian range were scattered on both sides of the new Atlantic Ocean.

“Things were beginning to break up when the dinosaurs roamed the Earth,” Anderson said.

Today, “folded-up, folded-over” Appalachian rocks, smoothed by generations of erosion, appear in bits and pieces all around the Atlantic basin – throughout Great Britain, Scandinavia, Greenland, Spain, France, Portugal, Morocco and Algeria. More recent research indicates that even the Shackleton Mountains in Antarctica may be of Appalachian origin, Anderson said.

“The rock formations [of different countries] all tell a story of that collision and breakup,” Anderson said.

“The evidence is there in the rocks.” Perhaps someday, this could be a truly international trail, with stretches in the 23 nations that share this common geologic heritage, Anderson said.

Last year, a popular British outdoor magazine featured the IAT, and the possibility of developing trails through the Caledonide range of Ireland and Scotland.

This weekend, even the hard rain that muddied the trail and fogged the glasses of the Carleton hikers couldn’t dampen their enthusiasm.

“So, 2014?” Hudson asked, the wind whipping his raincoat around his knees and sending water droplets soaring, as he rested at the summit of Mount Carleton.

“It’s a date,” Anderson replied.

For more information, visit the trail’s Web site at www.internationalat.org.