How was formed the spectacular geological wonder of the marble cathedral of Chile

At any time of the year, in the wild southern fringes of

Chile

the four seasons are mixed. The threatening clouds can intensify or dissipate in minutes and strong winds guarantee a constantly changing climate.

But this morning, early in the austral spring, when it rises on the shores of Lake General Carrera, the waters are calm.

The lake, a glacier-fed giant that crosses the border with Argentina and is one of the largest in South America, is home to one of the most spectacular natural wonders of

Patagonia

.

With its carved pillars, vaulted ceilings and ornate and textured walls, this unique geological formation on the western edge of the lake is known as the "Marble Cathedral" by the local population.

"When you arrive in the caves, there is a tranquility, a clarity, a synthesis of colors that you fall in love with," says visitor Hans Claussen.

Bathed in the blue

The cathedral is located a few meters from the coast, but the steep and wooded slopes behind only allow to approach it by boat.

In the morning, the master bedroom is in the shade and the light that enters the cave is reflected on the surface of the lake.

With its carved pillars, vaulted ceilings and ornate and textured walls, this unique geological formation on the western edge of the lake is known as the "marble cathedral" by the local population.

The deep turquoise color of the water, caused by glacial sediments, projects an ethereal blue hue on the gray and white surfaces, while the unique contours of the stone evoke astonishing compositions.

The sound of waves gently tapping against the walls echoes in the cave, accompanied by drops of water that constantly fall from the marble ceiling. Depending on the season, the lake level can vary considerably.

During the summer months, the meltwater of the surrounding mountains can raise the lake level by about one meter. In winter, the waters recede to reveal parts of the caves that are usually below the surface.

Color ribbons

The exposed colors are more than just a trick of light. Narrow strands of brown stone line the interior walls and yellow veins of the roof.

"When a rock is metamorphosed, new minerals are formed," says geologist Francisco Hervé.

The white marble sections are the purest, composed almost entirely of calcium carbonate, while the other shades of rock owe their color to various impurities.

The white marble sections are the purest, composed almost entirely of calcium carbonate, while the other shades of rock owe their color to various impurities.

Make wonderful marble

Small boats and kayaks can move slowly to the two main halls of the cathedral, allowing visitors to take a close look at complex texture surfaces. But the marvelous wonders of the lake do not stop there.

The natural sanctuary of Capillas de Mármol, which covers a coastal area of ​​50 hectares, is bordered by dozens of other caves and formations formed over millennia.

"We know that this area was covered with glaciers until 10,000 or 15,000 years ago," said Hervé.

"After the retreat of the glaciers, the lake was created, and that's when the process of carving the chapels began."

According to Hervé, the stone found in and around the caves probably was formed closer to the equator about 300 million years ago before slowly moving south due to drifting. continents. "They formed at temperatures of about 300ºC to 400ºC, between 10 and 15 km underground," he says.

"After the retreat of the glaciers, the lake was created, and that's when the process of carving the chapels began"

The rock began its epic journey in the form of sedimentary limestone, before the intense heat and pressure necessary for metamorphosis turned it into marble.

Compared to the hundreds of millions of years that marble has set to reach its present location, cave erosion has occurred in the blink of an eye, largely because of the properties stone chemicals.

"These limestone rocks, composed mainly of calcium carbonate, are among the most soluble," explains Hervé.

"People think that the pictures I took in the chapels are actually modern works of art, and when I tell them that they are marble caves, they are amazed," says Chelsea Dietsche, an American living in Chile.

A quiet life

Pedro Contreras moved to Puerto Río Tranquilo, on the west shore of the lake, while he was young and that he never left.

Thirty years ago, he was one of the first to bring intrepid tourists to visit the caves, but over the past decade, the number of visitors to the small town has grown rapidly.

"Previously, there were only three or four ships, now there are 50 ships coming and going to the cathedral," he says. "Everyone in Puerto Río Tranquilo works in tourism, they raised cattle."

The interest in the caves may have transformed Puerto Río Tranquilo, but the city has retained much of its border charm.

From each chimney silently smoke the germs of the wood that heats the houses during the harsh winters of Patagonia.

In the recently renovated city square, a sculpture depicts the first inhabitants of the region who sail on the lake.

Although some people are nostalgic of the most difficult times of antiquity, Contreras says that, overall, the modern world has improved life in the region.

"Things have changed a lot, but for the better," he admits. "Patagonia is more comfortable now."

Southern route

Before the tourists arrived the road. Large expanses of Patagonia were virtually isolated from the rest of Chile until the 1970s, when General Augusto Pinochet's military dictatorship engaged thousands of soldiers in the construction of a road in the region. ; Aysén.

Its construction required a herculean effort: from Puerto Montt, the road crosses fjords, mountains, glaciers and forests to wind more than 1,200 kilometers south of the town of Villa O. Higgins, at the border Argentina.

The highway, better known as Carretera Austral, opened Patagonia to the rest of Chile.

Although it is only a gravel road in some places, it remains the only artery that connects the north of the country to the region of Aysén.

Paradise of the virgin

In addition to being a lifeline for remote communities, the road has become a legend among travelers.

"The landscape in the region of Aysén is fascinating, you have to travel long distances to go anywhere, but at every step there is something new to see: an incredible landscape, a forest beautiful, wildlife, "said Pippa Mitchell. New Zealand visitor.

The route includes many natural wonders of Patagonia, such as Cerro Castillo, a mountain immediately recognizable by its turret-shaped turrets, central point of a multi-day trek that makes it more famous for strolling in the park . National Torres del Paine, further south.

Claussen, a visitor to the Chilean capital, Santiago, has been to the region several times and said that he would never tire of it.

"Aysén is my favorite place in the world," he says. "Time pbades more slowly, life is simpler, the immensity and the beauty of the landscapes make you feel both small and privileged.

"You are at the end of the world, where humanity has always had little impact."

The vast expanses of the road are full of unspoilt nature and, in 2017, the Chilean government signed an agreement with Tompkins Conservation to create more than four million hectares of new national parks in the surrounding area, guaranteeing as well as this one remains undeveloped.

Preserve the caves

Efforts to preserve Patagonia for future generations are beginning to spread in marble caves, and local tour operators are trying to minimize their impact.

"Before, you could go down [del barco] and take pictures, walk. But not anymore, "explains Gev Hervé, who hopes that the natural beauty of the caves can highlight the importance of preserving the other geological formations of the country.

"In Chile, the concept of biodiversity is very clear," he said. "But not geodiversity." He argues that the benefits of conserving sites such as the cathedral go beyond its obvious aesthetic appeal.

Over the course of 4.5 billion years of Earth's history, erupting volcanoes, rising or falling glaciers, as well as undulating sea levels have left their mark in the world. ;environment.

According to Hervé, many geological information recorded in the foundations of the stone chapels could provide us with invaluable knowledge about the fluctuations of Earth's temperature in the past.

"Things like climate change, for example, affect us all as a society," he said.

"These rocks could give us clues about the processes that have occurred in the past, why they happened, how we could prevent them from reproducing in the future."

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