View of the slate quarry and the CGA group.
Grotto on the lower right-hand corner and bedding above.
View of the bedding in the Valentia Slate  Formation.
Part of the quarry workings.
A sheet of slate  showing  traces of cutting by the saw.
Fort Point and Cahirciveen  from the quarry.
Tetrapod footprints at Dohilla.
Prof Higgs talking about the footprints.
Another view of the footprints.
Extension of the footprints.
General view of the surrounding environment.  Note glacial till.
Ripples on a loose rock.
The newly  discovered  trackway at   Coosdallisk.
Prof.  Ken Higgs discussing the newly discovered trackway.
A fold nearby in the Old Red Sandstone.
Another view of the spectacular  fold.
CGA members viewing  the fold.
View of the cliffs  near the  Valentia Coastguard Station.
Rocks near the cliffs.
Another view of the cliffs  near the Coastguard Station.
Conglomerate with CGA members in the background.
Conglomerate overlying siltstone and mudstone with quartz..
Prof. Higgs and CGA members on the cliff top, Doulos Head in the background.
Big ravine near the Coastguard  Radio Station.
View from the car-park to Fort Point and Cahirciveen.
Bedding or cleavage  - Trawaginnaun Bay.
Trawaginnaun Bay  - bedding or cleavage?
Myriapod  trackway barely visible to the left of the black line.
Folding near  Fort Point.

On Saturday morning, 27th April, 27 members of the Cork Geological Association gathered in Portmagee to begin a two-day trip along the north coast of Valentia Island.  Our leader and guide was Prof. Ken Higgs of UCC.  As we drove across the bridge there was every prospect of a fine sunny day with just a fresh westerly breeze.
The main rocks on the island belong to the Valentia Slate Formation, the oldest rock formation of the Old Red Sandstones in the whole Munster Basin.These Devonian rocks were deformed during the Variscan Orogeny towards the end of the Carboniferous Period about 300 million years ago.  This tectonic movement caused folding, faulting and even uplift of the rocks.  In the finer-grained rocks the great pressure produced the slate which gives the formation its name.  The excellent handout provided by our leader explains the geology of the area in great detail.
Our first stop was at the well-known Valentia Slate Quarry which was worked from 1816 to 1911 and re-opened again in 1998.  The slabs of slate were cut by large saws powered by steam engines.  The old spoil heaps are also searched for suitable material.  In the cliff face at the entrance the purple siltstones dip gently to the northwest while the cleavage dips steeply to the southeast.
Next we moved down to the fossil trackway  on the shore at Dohilla.  Here we see the footprints of a tetropod (translates as 'four feet')  the earliest known animal to walk on land. It's the  second oldest evidence in the world of such a four-legged vertibrate moving from water on to land and was discovered  in 1993 by a Swiss geology student, Ian Stossel.  Prof. Higgs explained all  about the size and shape of the tetrapod, how he moved across the muddy coastal plain and how the fossil prints can be dated to around 385 million years ago.   The trackway appears on a bedding plane of purple sandstone and siltstones and the beds in the area are gently folded.
We then moved a short distance away to a new tetrapod trackway which was discovered in 2011 at Coosdallisk.  Again the fossil prints are in fine-grained sandstone but they seem to belong to a smaller or maybe younger animal  who also moved more slowly along the sand flats beside a river channel.
After lunch in Knightstown we made a short  visit to the  museum housed in the old schoolhouse. Then followed the long walk  to Reenadrolaun  Point.  Here the younger beds of the Valentia Slate Formation consist mainly of fine-grained purple siltstones.   Their steep cliffs show the stark erosive effect of the Atlantic storm waves.  Here also is a mafic volcano tuff and an unusual pebbly conglomerate with rare metamorphic clasts.
The rocks of the Valentia Slate Formation on Trawaginnaun Bay were the subject of a disussion on whether they showed bedding or cleavage.  Near Fort  Point Lighthouse we saw some small Myriapod trackways called Diplichnites in the siltstone.  A myriapod is a type of small arthropod that resembles a millipede and probably  lived in small ponds on the river floodplains.


Click on the photo gallery below to view pictures of the trip.
Double click here to add text.