Ring Fort Near Kilcar Co. Donegal

A photograph of a ring fort from late pre-christian or early christian times near Kilcar Village, Donegal.

Tawny Bay is in the background. The photo was taken from the coast road between Kilcar and Carrick. These are also called fairy forts and it is said that fairies may be seen dancing in them under a full moon. I did not see any fairies, but maybe I was there at the wrong time. The remains of an old stone pier are on the far side of the bay. It appears to me that the land has risen so much relative to sea level that the pier is no longer useful

This ring fort was likely on an island 1000 years ago. On an old map, I saw a mention that local people named it island. The ice of the last ice age was so heavy that it depressed the earth and it is springing back now that the ice is gone. This rising of the land is fastest in northwest Ireland and is very fast in geological time, but very slow as people experience it. The land in much of Ireland has been rising faster than mean sea level has been rising for the last few thousand years. For the earth as a whole, sea level has been rising, but in North West Ireland, the land has been rising faster than sea level so that relative sea level (RSL) has been falling. If the Greenland ice cap or the West Antarctic ice cape were to rapidly melt in the next several decades, then sea level will rise much faster.

One paper says that the relative sea level fell about 6-7 cm/year. Sea-level change and inner shelf stratigraphy off Northern Ireland
Joseph T. Kelley a,., J. Andrew G. Cooper b, Derek W.T. Jackson b, Daniel F. Belknap a, Rory J. Quinn b a Department of Earth Sciences, University of Maine, Orono, ME 04469-5790, USA b School of Environmental Science, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK Received 15 January 2006; received in revised form 22 March 2006; accepted 2 April 2006 https://www.sciencedirect.com/science/article/abs/pii/S0025322706000909 http://www.science.ulster.ac.uk/cma/kelleyetal2006.pdf

New seismic stratigraphic, vibracore and AMS 14C dates from two sites off the Northern Ireland coast yield information on the deglacial to present sea-level history and shelf evolution of the region. A lowstand of sea level at about 30 m below present sea level recorded by fossils in a lowstand shoreline deposit occurred around 13.4 cal ka B.P. following a period of rapid isostatic uplift associated with a RSL fall of 6.7 cm/yr.

Following the lowstand, contrasting styles of sedimentation characterized the two study sites. In the sheltered environment of Belfast Lough, the lowstand shoreline was overtopped and buried by transgressive facies of intertidal and shallow sub-tidal mud and sandy mud. On the high-energy Portrush coast, the inner shelf sedimentary sequence is characterized by a basal conglomerate overlain by well-sorted sands with occasional interbedded gravel. Copyright 2006 Elsevier B.V. All rights reserved.

I also photographed a ring fort in County Kerry in May 2007. There is a large, famous ring fort in northern County Donegal near Inishowen.

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A ring fort on a hill next to stone fences and Tawny Bay near Kilcar,
Donegal.

https://onlinelibrary.wiley.com/doi/abs/10.1002/jqs.1116
The Donegal ice dome, northwest Ireland: dimensions and chronology
Colin K. Ballantyne 1 *, Danny McCarroll 2, John O. Stone 3 1School of Geography and Geosciences, University of St Andrews, Fife, Scotland, UK 2Department of Geography, University of Wales Swansea, Swansea, Wales, UK 3Department of Earth and Space Sciences and Quaternary Research Center, University of Washington, Seattle, Washington, USA email: Colin K. Ballantyne (ckb@st-and.ac.uk) *Correspondence to Colin K. Ballantyne, School of Geography and Geosciences, University of St Andrews, Fife KY16 9AL, Scotland, UK. Ballantyne, C. K., McCarroll, D. and Stone, J. O. 2007. The Donegal ice dome, northwest Ireland: dimensions and chronology. J. Quaternary Sci., Vol. 22 pp. 773-783. ISSN 0267-8179.

Geomorphological evidence indicates that Donegal was formerly occupied by an ice dome that extended offshore to the west, northwest and north and was confluent with adjacent ice masses to the east and south. Erosive warm‐based ice over‐rode almost all the highest mountains, implying an ice‐divide altitude greater than 700 m. Only six peripheral summits escaped glacial modification, implying either that they remained above the ice surface as nunataks or supported a thin cover of protective cold‐based ice. Gibbsite, a pre‐last glacial weathering product, is preferentially represented on summits that escaped glacial modification. Cosmogenic 10Be exposure ages of 18.6 ± 1.4 to 15.9 ± 1.0 k yr for coastal sites confirm that Donegal ice extended offshore at the last glacial maximum. Reconstruction of the form of the Donegal ice dome suggests a former minimum ice thickness of ∼500 m close to the present coastline in the west and northwest, and ∼400 m near the coast of the Inishowen Peninsula in the north, with the ice extending at least 20 km across the adjacent shelf to the west and northwest. Copyright © 2007 John Wiley & Sons, Ltd.

Postglacial relative sea‐level observations from Ireland and their role in glacial rebound modelling† Anthony J. Brooks Sarah L. Bradley Robin J. Edwards Glenn A. Milne Ben Horton Ian Shennan First published: 01 October 2007 https://doi.org/10.1002/jqs.1119 https://onlinelibrary.wiley.com/doi/abs/10.1002/jqs.1119

The second misfit concerns the presence of a Holocene highstand (commonly around 6000 BP), where ongoing crustal rebound starts to outpace dwindling sea-level rise.

Deglaciation chronology of the Donegal Ice Centre, north‐west Ireland Peter Wilson Colin K. Ballantyne Sara Benetti David Small Derek Fabel Chris D. Clark First published: 11 December 2018 https://doi.org/10.1002/jqs.3077 https://onlinelibrary.wiley.com/doi/10.1002/jqs.3077 http://eprints.whiterose.ac.uk/142756/1/Wilson_et_al-2019-Journal_of_Quaternary_Science.pdf

Abstract
During the Last Glacial Maximum, Donegal in north‐west Ireland functioned as an independent centre of ice dispersal that separated and fed into the Donegal Bay Ice Lobe (sourced in the Irish Midlands) to the south and the Hebrides/Malin Sea Ice Stream to the north. We report geochronological data that demonstrate marked contrasts in the timing and rate of deglaciation in northern and southern Donegal. In northern Donegal, which occupied an inter‐ice‐stream/lobe location, decoupling from the Hebrides/Malin Sea Ice Stream resulted in formation of a marine embayment along the north coast by ∼22–21 ka, and subsequent slow (∼4 ± 1 m a−1) climatically driven inland retreat of the ice margin to mountain source areas by ∼17 ka. By contrast, in southern Donegal, which lay near the axis of the Donegal Bay Ice Lobe, deglaciation was delayed until ∼18 ka following readvance of ice to a moraine in outer Donegal Bay. The ice margin subsequently underwent net retreat, apparently uninterrupted by readvances, at a net rate of ∼ 18 ± 6 m a−1. A mean terrestrial cosmogenic nuclide age of ∼15.0 ka obtained for samples from the foothills of the Blue Stack Mountains in south‐east Donegal indicates that ice persisted in valley heads and cirques at the beginning of the Lateglacial Interstadial, suggesting that these and nearby mountains supported the last remnants of the Irish Ice Sheet before complete deglaciation of Ireland, and that almost all the shrinkage of the ice sheet in this sector occurred under stadial conditions before the onset of interstadial warming at ∼14.7 ka.