Burren footprint mystery solved

A GIANT footprint visible on the landscape from the sky above the Burren has turned out to have very natural origins.

The mysterious shoeprint is approximately 116m in length and ranges in width from 28m to 37m. It was spotted in a Google Earth image of the Burren but can be easily explained, according to a local geologist.
The Burren and Cliffs of Moher Geopark received the image from a member of the public last week.
On investigation, geopark geologist Dr Eamon Doyle said the image is that of a doline, which can be formed by solution of the limestone by rainwater or the collapse of underground caverns or rivers.
The site of the geological feature is located on the coast between Doolin village and Ballyrean, a location made famous in storyteller Eddie Lenihan’s tales about the legendary Finn and the Fianna.
Commenting on what he described as the Burren’s “carbon footprint”, Dr Doyle stated, “Dolines are bowl-shaped, enclosed depressions in the land surface that can be several metres to several hundreds of metres wide. They can form by the dissolution of limestone from the surface downwards or by the collapse of overlying rock into a cave or by a combination of these processes.”
There are thousands of dolines in the Burren, which is also home to Europe’s largest doline. The Carran Depression is one of the oldest features in the Burren landscape and is understood to have developed before the last ice age, two million years ago.
“There are at least 1,500 dolines in the Burren that have an area greater than 100m2. Most of these larger dolines occur in the east of the Burren. This is because large dolines take tens of thousands of years to form and the eastern parts of the Burren have been affected by dissolution longer than the west. However, the footprint-shaped doline in this image was discovered in the west of the region, just a few hundred yards from the Atlantic coastline.
“It is thought some of the larger enclosed depressions in the Burren began to form when the area was still covered by shale. A river or rivers flowing over the shale eventually cut down into the limestone underneath and would have been diverted underground. Once even a small window of limestone was exposed, it would have been gradually enlarged by dissolution from run-off,” Dr Doyle outlined.
Dr Doyle also said while it is difficult to tell whether or not the doline will sink any further, he believes it will not.
“The base of it is a plateau. This would indicate it has reached an impermeable layer of rock,” he said.
The footprint-shape of the doline is also easily explained.
“It is likely that what we can see there is two dolines coalescing. They would be like two circles overlapping and then you get this kind of shape,” Dr Doyle concluded.
More information on the Burren and Cliffs of Moher Geopark is available from www.burren.ie.