Heavy rain has produced dangerous mud slides along the coast.
Those heading to Charmouth have been warned not to attempt to climb over the flowing mud and to look at them from a safe distance.
Martin Curtis, of Jurassic Coast Guides, says the phenomenon happens when the soft shale in the cliffs become saturated and heavy after it rains and consequently falls down on to the upper ledges with in the cliff areas.
After further rain the material softens, eventually turning to mud and flowing down to the beach.
"These mud flows are very common during the wet winter months and is part of the natural erosion on the Jurassic Coast," said Mr Curtis. "They are, however, very dangerous and should never be climbed over. If you are on the beach, please admire from a safe distance and do not attempt to climb over them."
Warnings are not always followed, and Mr Curtis says rescues from the mud flows are very common at Charmouth and often result in the use of a helicopter to assist emergencies services.
"If anybody gets into any kind of difficulty on the Jurassic Coast they must dial 999 and ask for the coastguard," he said.
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