By James Robinson for MailOnline
Published: 11:17 EDT, 10 January 2022 | Updated: 06:46 EDT, 12 January 2022
It was once just a small hole in the ground, providing a minor inconvenience to local joggers and dog walkers coming to enjoy the views over the rugged cliffs.
But the once man-sized Souter Hole at Whitburn, near Sunderland, has now become a 40ft-wide awe-inspiring giant.
The massive 'sinkhole' first appeared as a small hole in the ground in 2003. But through erosion and landslips the natural phenomenon has grown and grown.
Now it is so big that a hidden beach has been carved out inside, with the sea forcing its way through a crack in one of the cliff walls.
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Erosion and landslips have left a gaping hole on a field leading to the cliffs at Whitburn, near Sunderland
But the once man-sized Souter Hole at Whitburn, near Sunderland, has now become a 40ft-wide monster - and in doing so has revealed a secret
Beach artist Clair Eason, a former GP, captured the true extent of the sinkhole while exploring the coastline near her home.
She said: 'This deep sink hole near Souter Point, South Shields, began as a small hollow a few years ago.
'It's growing into a huge beast, adding even more drama to the rugged coastline.'
Experts say the giant sinkhole, also known in geological terms as a 'doline', most likely formed through sea water being pushed through a fault in the limestone cliffs.
British Geological Survey's Shallow Geohazards and Risks team leader, Vanessa Banks, said such sinkholes are not uncommon in coastal areas like Whitburn.
Dr Banks, who has studied geology for 40 years, told MailOnline: 'Dolines are often formed where you have cold water and glacial sand and gravel deposits underlain by soluble rocks such as dolomitized limestone or gypsum.'
Dr Banks said that it was likely the hole may have already been an area of depression, with softer sediments and eroded limestone collapsing down towards the interface of groundwater and seawater sea water being pushed via tides through a developing cave - known in geological terms as a conduit.
'These processes may have started towards the end of the last glaciation,' said Dr Banks
The giant 'sinkhole' first appeared as a small hole in the ground in 2003. But through erosion and landslips the natural phenomenon has grown and grown
The National Trust has been forced to cordone off the sinkhole which is close to the cliff coast path
'Once a void has formed it will enlarge due to stress relief at its sides and from below.'
Asked how the beach at the base of the sinkhole had formed, Dr Banks said: 'There will be two reasons, the first is standard collapsing from above and also the water moving sediment in during high tide.'
The National Trust, which manages the cliff path around the sinkhole, are warning walkers and dog owners to avoid the area.
The charity has been forced to cordoned off the sinkhole which is close to the cliff coast path.
A spokesperson said: 'We want all of our visitors to have an enjoyable, relaxed and safe visit to Whitburn Coastal Park.
'By its nature the coastline is constantly changing, with some areas particularly prone to erosion and landslips.
The National Trust, which manages the cliff path around the sinkhole, are warning walkers and dog owners to avoid the area
'This sink hole first appeared around 2003 and is regularly surveyed.
'We have put up fencing and warning signs around this sink hole, which is away from the main path running along the cliff tops of The Leas and Whitburn Coastal Park, known locally as The Wherry.
'There are warning signs at key points along the cliff edges, as well as visitor information panels in each car park.
'We'd urge people to take a moment to look at these signs, and to stick to the main paths to keep themselves, their children, and their dogs safe.'
It's been at least 20 feet across for many years a...
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