for National Geographic News
An unusually large stretch of Britain's famous white cliffs collapsed recently. The loss of the quarter-mile (400-meter) section dumped a hundred thousand tons of chalk into the sea and left many people worried that natural erosion of the beloved landmark is occurring at an accelerated rate.
Meanwhile, west of Dover, another landslide brought down part of the 200-foot-high (60-meter) cliff face, including the famed Devil's Chimney.
Could environmental changes caused by factors such as global warming trigger bigger and more frequent landslides?
Not so, said Steven Judd, countryside manager for the National Trust, the environmental body that owns most of the Dover coast. "I see no evidence to suggest that," he said.
The cliffs recede at an erratic rate, he said: "Averaged out over a few hundred years, the annual rate works out at only one centimeter (half an inch) a year."
Over the past year, however, Britain experienced the highest level of precipitation since record-keeping began 200 years ago. The heavy rains accelerated the erosion process dramatically, causing parts of the coast to cave in spectacularly.
While Judd views the erosion of the cliffs as natural and gradual, the collapse of large sections poses increased risks. Cliff-top structures, including lighthouses, have had to be moved to safer sites inland. And walking trails, which offer dramatic views from atop the cliffs, have been relocated farther from the crumbling edges.
Immortalized in lyrics and verse, the "White Cliffs of Dover" are an icon of English patriotism and nostalgiaa familiar landmark for returning travelers akin to the Statue of Liberty for Americans.
Facing the English Channel at the point nearest to the French coast, the 300-foot-high (90-meter-high) cliffs have also been a bastion to foreign invaders throughout history.
Before the Ice Age, Britain and France were linked by a chalk land mass. Over time, it was eroded away by tidal movements, creating the English Channel. There are matching white cliffs on the French coast.
Hidden deep underground in the white cliffs are miles of tunnels built during the Middle Ages under Dover Castle. They provided protected communication lines for garrisoned soldiers as they prepared to launch surprise attacks against enemy invasions from across the Channel.
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