Burren and Cliffs of Moher UNESCO Global Geopark - Geology

The significance of Slieve Elva.
At 344m above sea-level, Slieve Elva (Sliabh Eilbhe) is
the highest point in the Burren region. As a landscape
feature it records the past, influences the present and will
contribute to the future Burren landscape.
Slieve Elva is surrounded by limestone on its western,
eastern, and northern slopes but the top is not limestone,
it is mostly shale with some layers of sandstone, which are
largely covered by a bog. These are the same shales and
sandstones that stretch south to form the cliffs at Doolin
and the Cliffs of Moher. The change from limestone to
shale is abrupt and we know from fossils that there is a
time gap (a few million years) between the last limestone
being formed and the first shale being formed. We are
not exactly sure what happened during that missing time
period.
The sandstones and shales that make the top of Slieve
Elva are a just remnant of what would have covered all
of the Burren millions of years ago. Erosion by rivers,
and then ice, has removed these rock layers, exposing the
limestone underneath. Once exposed, the limestone is
then subject to the influence of rainwater which dissolves
the limestone. This is demonstrated particularly well
around the flanks of Slieve Elva where a large number of
sinkholes have developed at the contact between the shale
and the exposed limestone. This has had a huge impact
on the Burren over millions of years; the current Burren
landscape would not have developed if the limestone was
still buried under sandstone and shale.
However, it is not just the rocks of Slieve Elva that are
significant, the bog that caps the mountain has a very
important influence on water flow in the area. The bog
acts as a living water storage system that can hold water
and release it slowly throughout the year. This means that
the local streams always have water, although they flow
underground through the limestone for some of their
journey. One of those streams, the Gowlaun River at
Lisdoonvarna, is fed directly by water that flows off Slieve
Elva. If you visit the Spa Wells in Lisdoonvarna after a
recent rainfall event you will be able to see where the two
distinctive rivers meet. The clear water of the Gowlaun
River meets the dark water of the Aille.
We are currently working with hydrologist Dr. Tiernan
Henry of NUIG to monitor the water flow and develop a
better understanding of how the complex river catchment
works and how it will change based on climate change
predictions for rainfall changes in the coming years. This
ties in with the work of Lisdoonvarna citizen scientists in
the Aille Engaged project who collect daily rainfall and
river level data.
Figure caption: The clear water of the Gowlaun River (left) meets the dark water of the Aille River (right) at the Spa Wells.