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Moonscape?

Yikes, those grikes!

Erratic behavior

Kamenitza

Underground alien

Careful now

Rock garden

The wall

Seastack

Portal tomb

Crash!

Castles, castles everywhere

COUNTY CLARE, Ireland -- With miles and miles of silvery-gray stone, the Burren could easily stand in for the moon in a sci-fi film. At one time, this entire region on Ireland's west coast was submerged under the ocean, and layers of sediment, along with fossils and embedded shells, are easily seen in the exposed rock.

While the Burren may look like a desolate rockscape, there are plenty of flowers and grasses flourishing in the cracks found in the limestone that blankets the area. In some regions, enterprising farmers created topsoil by applying layers of seaweed and sand on top of the stone. While that layer of soil is sufficient for grazing for the sheep and cows that roam around pens hemmed in by ancient stone walls, it's not really adequate for raising crops or growing trees.

Caption by / Photo by Michael Franco/CNET

The Burren's moonlike terrain is the result of karstification, a process by which erosion creates an exposed-limestone topography dotted with fissures, sinks, ravines and underground streams.

One of the most striking features of the Burren is its series of grikes and clints. Grikes are long straight fissures that form as rain wears away natural cracks in the limestone, while clints are the blocks of stone found between them. Water drains through the grikes to fill hidden underground lakes and rivers. Sometimes that water bubbles up to the surface in springs or in turloughs, lakes that appear and then disappear again -- sometimes in a matter of hours.

Caption by / Photo by Michael Franco/CNET

Two ice ages pushed massive glaciers through the Burren as it was forming. When the glaciers melted, they left behind large boulders known as glacial erratics that dot the landscape. While they make for a great tourist attraction, homeowners and farmers have to be content to leave the massively heavy balls of rock where they've sat for thousands of years.

Caption by / Photo by Michael Franco/CNET

While they might sound like a Greek pastry, kamenitza are actually small holes found in the Burren's limestone surface. They are formed when rainwater sits on a stone. Because rainwater is slightly acidic, it dissolves the limestone, leaving behind these little pools.

This image also shows how tenacious wildflowers can blossom in a land where soil is at a premium.

Caption by / Photo by Michael Franco/CNET

The Doolin Cave, found in -- you guessed it -- the town of Doolin, is home to the third largest stalactite in the world. Its alien-like form hanging from the cave's ceiling is created as calcium deposits brought into the cave through groundwater are deposited on its tip.

The stalactite weighs 10.5 tons and measures 24 feet (7.3 meters) in length.

The left side of the stalactite is "dead," as calcium deposits sealed up the water that was fueling its growth about 300,000 to 500,000 years ago. The right side is still growing -- at the rate of a half-inch every 100 years.

Caption by / Photo by Michael Franco/CNET

The unique fanlike twisting pattern of the stalactite has come about through the action of wind that entered the cave through a now-sealed passageway.

According to Doolin Cave tour guide Tristan O'Callaghan, the stalactite was first discovered in 1952 by explorers Brian Varley and Mike Dickinson. They crawled on their bellies through extremely tight passageways for 2.5 hours to reach it.

To turn the stalactite into a more accessible tourist-friendly attraction, a rock-breaking method called "plug and feather" was used. This involved making holes in the stone walls of the cave by hand and then breaking the stone out using compressed air. While automated drilling equipment would have made the job go much faster than the year it took to create the wide passageway, conservationists were worried about vibrations damaging the integrity of the stalactite.

Caption by / Photo by Michael Franco/CNET

When you first see the Burren, it's easy to think nothing could ever grow there. However, there's an astounding assortment of plant life that thrives in the cracks and crevices of the limestone topography, which is sometimes referred to as "fertile rock." In fact, one study found that the region is home to 635 different species of plants.

One of the most striking features of the Burren's flora is that arctic-alpine plants -- like the spring gentian seen here -- grow right next to plants normally found in the warmer Mediterranean region. The former simply stayed on in the Burren when the last ice age ended and the later can thrive because of the warming features of the Gulf Stream along with the fact that limestone is great at retaining the sun's warmth and creating microclimates that allow plants found in more southerly regions to thrive.

The Burren is also home to 22 of Ireland's orchid species.

Caption by / Photo by Michael Franco/CNET

At the southern reaches of the Burren are the dramatic Cliffs of Moher, which bring The Wall in "Game of Thrones" to mind. These dizzying cliffs plunge 702 feet (214 meters) to the icy Atlantic below and stretch approximately 5 miles along the border of County Clare.

The cliffs formed when layers of sandstone, siltstone, mudstone and shale that were deposited over 300 million years ago by a river were forced upward through the movement of the Earth's plates.

Caption by / Photo by Michael Franco/CNET

At the base of the Cliffs of Moher is this dramatic "seastack," which juts skyward to a height of 220 feet (67 meters). It was once part of the cliffs, but coastal erosion eventually dissolved the rock joining the two.

The seastack and the cliffs themselves are homes to a stunning array of bird life. April to July is nesting season, when more than 20 species of birds and over 30,000 pairs of seabirds can be found. The seastack serves as home to hundreds of guillemots, a bird that looks a bit like a penguin. The guillemots lay their eggs on precarious cliff edges, but thanks to unique nano-structures like a rougher shell casing, the eggs don't fall off.

Caption by / Photo by Michael Franco/CNET

The Burren is dotted with tombs dating from the neolithic period (about 9,000 B.C. to 3,000 B.C.), including this one called Poulnabrone. The structure is considered a portal tomb as distinguished by its stone walls and large capstone. It's not clear how the massive stones were put into place.

When the tomb was excavated, the remains of 16 adults and six children were found. The bones had been taken apart and some had char marks on them from fire, which has led investigators to theorize that the bodies were first stored elsewhere and allowed to decompose before being relocated to Poulnabrone in what was likely a ritual burial for powerful families.

Caption by / Photo by Michael Franco/CNET

The Burren's rocky landscape extends to the nearby Aran Islands. Inisheer is the smallest of the three islands and holds a population of just under 250. It has a fairytale feeling to it, helped along by this shipwreck on its coast.

The ship, called the Plassey, crashed on something known as the Finnish Rock in 1960 and was later washed ashore during a violent storm. Thanks to the help of the islanders, all the crew members survived.

Caption by / Photo by Michael Franco/CNET

Adding to the "Game of Thrones" feel of the Burren are dozens of stone castles standing on hilltops throughout the territory. This castle, known as Ballinalacken, is believed to have been built in the 15th or 16th century and is still remarkably intact. It's now privately owned and can only be visited by those staying at a hotel on the grounds.

Caption by / Photo by Michael Franco/CNET
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