Díseart,
Institute of Education and Celtic
Culture.
Dingle,
Co. Kerry,
Ireland.
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| Dingle
Historical Society Presents |
GEOLOGY OF THE DINGLE
PENINSULA
Illustrated Lecture by Bernard Goggin at An
Díseart Dingle 28th July 2005 at 8 p.m. |
The geology of the Dingle Peninsula is the story of the
Iapetus Ocean and the final closure of it just north of the peninsula during
the Ordivician and Silurian Periods.
This area was a continental shelf
on the north side of the Avalonia (western Europe) at the beginning of the
Ordivician Period some 500 million years ago. Far to the north was Laurentia
(North America). These sediments lie under Annascaul highly distorted by
tectonic forces.
The plates met creating volcanic islands and shallow
tropical seas full of marine life, now fossilised at Dunquin. When the
subduction of the Iapetus Ocean floor under ended a climactic eruption created
the massive pyroclastic flow at Clogher Head. The two plates finally were fused
and the Old Red Sandstone continent emerged. The suture now to found only by
magnetic anomalies.
However the great pressures formed massive
transpressive sinistral faults. Geothermals on the zone made the mineral
deposits in the midlands of Ireland. The peninsula was now a valley bounded by
a great fault to the south of Dingle Bay Lineament, and to the north the North
Kerry Lineament. A shallow lake covered the area some 50 by 30 kilometres and
its floor is well displayed on the cliffs of Eask and at Dunquin Harbour.
Six kilometres of sediment filled the basin due to local uplift in a
complex sequence leaving in the rock record remains of dune fields, great fans
of conglomerate, river bed forms of a very large river, the present day
analogue is the mighty Bramaputra in India. The last pulse of the Caledonian
Orogeny, the Acadian, pushed up the desert sediments into a mountain range like
the Himalayas.
Within the ORS time this was worn down and the final
layers were deposited as part of the Munster Basin, well displayed at Trabeg.
The seas returned and covered the area with the Carboniferous
limestones exposed in the Maharees.
Finally the Hercynian mountain
uplift folded these sediments into the present day mountain ranges of Munster
created the bays as synclines.
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| Díseart, Institute of
Education and Celtic Culture. Dingle, Co. Kerry, Ireland. |
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