On Tuesday, a viewing platform fell from the beach on the Paldiski shore together with a broken piece of the shore. Now people are worried when the rest of the bank will disappear into the sea. According to Olle Hints, associate professor of rock geology at Tallinn University, the shoreline will move about 25 meters landward in 100 years.
“There is nothing special here. These processes have been going on for thousands of years and will continue. Nor can man resist this force of nature,” commented Hints.
The old Pakri lighthouse, built in 1760, was once safely away from the sea. Now the ruins of the lighthouse are about to disappear into the sea. “This disintegration of the coastal shore is here piece by piece. The lower part is continually crumbling away, from where the sea, wind and waves investigate, but the limestones of the upper part bide their time. If the lower part is empty, such collapses will happen after a while,” Hints said.
One of the largest collapses occurred in 2008, when an estimated twenty thousand tons of soil collapsed. At that time, the local government also thought about artificially burying the most dangerous places with explosives. However, it didn’t come to that.
According to Hints, it is very difficult to predict when the next collapse might occur, but the erosion process is continuous and on average the shore moves about 25 meters landward in 100 years. Therefore, according to Hints, in 300 years even Estonia’s tallest lighthouse will be in danger.
Collapses usually occur in winter and spring. “There are several reasons for this: the wind is stronger, the waves are stronger, but the ice is also what affects it. Everything is frozen on the surface, but underground water still moves inside the rocks. It arrives in the cracks, it freezes, expands and starts to break it down.” Hints explained.
Therefore, the local government has mapped even the most dangerous places on the coastal coast. “We don’t look at it nervously, we know the processes of the sea,” said Lääne-Harju deputy mayor Erki Ruben. “These processes still happen unexpectedly, that’s what these warning signs are for, you have to be extremely careful when moving here,” he added.
Tips explained that the coast of the shore is a good archive of the world history of the Ordovician and Cambrian eras. “The entire time span in those 25 meters is 50 to 60 million years, which we can read like a history book,” she said.
The lower layer consists of loose sandstone. The next layer is mud or graptolite shale or “black shale”, which, according to Hints, also contains a significant amount of uranium. Above is more sandstone, this time a greenish color, given to the stone by a mineral called galuconite. However, the upper third is limestone.
According to Hints, material that falls into the sea shatters and the waves carry it elsewhere, where it reforms on land.
2024-01-19 18:42:00
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