Massive ‘hole’ in mountain baffles locals with some saying it’s ‘Devil’s bumhole’

The ominous looking feature in Eryri (Snowdonia) is not quite what it seems – when a photo was shared online, asking for answers, it left people floundering for explanations

From afar, ramblers can gaze upon a hillside formation that some have compared to the “Devil’s bumhole”. According to local folklore, this enormous crater was created by an errant missile launched from a Ministry of Defence testing facility further along the Welsh coastline.

However, the menacing-looking landmark in Eryri (Snowdonia) isn’t quite as it appears. When an image was posted online seeking explanations, it sent people scrambling for answers. In the absence of concrete information, numerous theories emerged. Given its position on a hillside north of Abergynolwyn in Gwynedd’s Dysynni Valley, the most logical conclusion seemed to be an abandoned slate quarry.

The region boasts extensive mining history, with Abergynolwyn originally constructed to house quarry labourers. However, the area’s largest slate operation sits on the valley’s opposite flank.

This was Bryn Eglwys quarry, which prompted the construction of Talyllyn Railway to ferry slate down to coastal Tywyn, reports North Wales Live.

Could it have been the location of an aircraft accident, some speculated?

Several crash sites exist nearby, most notably a Flying Fortress bomber that plummeted shortly after World War II ended in Europe, allegedly laden with gifts for the airmen’s relatives in America. The tragedy claimed all 20 crew members and passengers.

Once more, the positioning didn’t match: the actual crash occurred on the mountain range’s far side, near Craig Cwm Llwyd’s peak on the Mawddach Estuary’s southern edge. Join the North Wales Live Whatsapp community now Predictably, other suggestions were more eccentric and tongue-in-cheek.

Some drew inspiration from folklore, envisioning it as some sort of “dragon’s lair” or possibly even the “door to Mordor”. Others cheekily suggested it was “the Government’s £22bn black hole”.

The truth proved far less exciting. “It’s just the angle of the sun and subsequent shadow exaggerating the depth,” clarified one individual online.

Beneath the ridge lies a broad hollow, roughly 100 metres wide, where a seasonal stream flows during winter. It’s enclosed below by another ridge, forming a natural hillside basin that captures light when the sun strikes at precisely the right angle.

The apparent “smoke” is merely the shifting of tiny shadows.

Mountain shadows can play tricks on the eye and, occasionally, they become cherished landmarks. The most renowned is the Brenhines yr Wyddfa (Queen of Snowdon) shadow cast upon Derlwyn’s slopes, a modest peak sitting below Wales’ tallest mountain.

This shadow appears to depict a woman’s silhouette, resembling a figure you might find on a postage stamp.

Another shadowy outline exists in the same vicinity, at Yr Wyddfa’s (Snowdon’s) base. Spotted less frequently, this formation has been connected to the child-stealing Tylwyth Teg (Welsh fairy) linked to a neighbouring lake.

In recent times, its prominent jaw and elaborate mane have drawn comparisons to a particular US president. The Dysynni Valley brims with ancient prehistoric and Romano-British remnants.

Close to the “hole in the mountain” sits Craig Ty’n-y-Cornel, a hilltop archaeological location where a tiny settlement thrived for centuries and potentially millennia.

Regarded as a monument of national significance, it gazes across the valley towards Craig yr Aderyn hillfort, a prominent local landmark that’s hard to miss – known alternatively as Bird Rock.

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