Weather and erosion - what's behind huge Jurassic Coast cliff fall?

  • Drone footage captures the scale of the rock fall

During the early hours of Tuesday 13 April a huge section of the cliffs adjacent to Seatown fell onto the beach and into the sea.

It was the biggest rock fall in 60 years, leaving trees and vegetation previously 300-400ft up poking out of the English Channel.

This part of the Jurassic coastline is prone to these types of landslips mainly due to the rock structure. Sandy rocks sit on top of clay and as the cliffs are exposed to the weather and suffer erosion the layers of rock are weakened and become unstable.

Weather plays a part in this as rain water seeps into cracks and joints, saturating the ground. The type of temperature extremes we have had over the past few weeks hasn't helped either, with very warm days followed by frosty nights. This causes the water within the rock to freeze and expand, opening up pores and causing fractures.

Trees, vegetation and nesting birds also slowly break down the make up of the cliffs. It is a slow process until the point of collapse, which is unpredictable, sudden and often dramatic. Thankfully the timing of this cliff fall meant nobody was hurt.

  • Geologist Jodi Brewin explains the causes of cliff falls

She told ITV News: "A massive load of debris has come down. This is an active coastline, slips happen all the time - but just not to this extent."

She said weather and erosion "play hand in hand", adding: "They both shape this coastline.

"With the weathering, we have had cold weather, we have had freezing weather which has opened up fissures in the ground."

People are being advised to stay well away from the debris on the beach and the cliff top edge.

The ground is still very unstable with new cracks opening up, so although it appears quiet and safe other falls are possible and it is not worth risking it for that close up shot or fossil find.

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