Header image The Dúns of Aran:

Tsunami Shelters ?
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Evidence for TSUNAMI / WAVE shelters

    • Massive thickness of Dún walls would be extremely effective in deflecting the power of Tsunami waves
    • Chevaux de Frise – would dissipate wave power, similar to modern seawall defences
    • Circular design of the forts provides a more effective structural defence from waves than rectangular model.
    • Wall batter also helps to deflect power of waves similar to modern sea-walls.
    • The Terraces inside the Dúns would help catch falling rocks and debris
    • The presence of clochans (small circular stone huts) and chambers in walls would protect inhabitants from rocks falling into the enclosure or propelled by waves.
    • Clochans and chambers may also have been used to store boats for escape by sea.
    • The outer walls of the forts may have afforded initial shelter from the first wave as people rushed to the much stronger inner enclosure or may have been used as protetion for animals.
    • The geographic spread of forts would have allowed inhabitants a chance to reach the nearest fort prior to first wave.
    • The presence of hundreds of granite boulders amongst the limestone rocks near Dún Cathair could have derived from either sea storms or Tsunami at a time of high sea levels or when the islands were submerged.
    • Simlarly the presence of raised beaches on top of cliffs on Inis Meain and Inis Mór relate to a time of higher sea levels and/or depressed land prior to isostatic rebound.
    • The excavations to date on Dún Aengus and Dún Eoghanacht both recorded significant finds of shellfish midden deposits. Some of this midden was embedded deep into grykes in the bedrock. I would suggest this is evidence of the forts being inundated for a period.
    • Also, why keep tons of shellfish midden in the Dún Aengus enclosure when you are beside a cliff?
    • None of the forts contain granite boulders in their walls proving they were built before whatever incident delivered the granite boulders onto the islands.
    • Folklore mentioning Galway bay (Loch Lurgan) once being a lake and the Islands being linked to Clare supports the idea of a time prior to cliff creation and lower sea-levels.
    • Theories of the Dúns being castles or fortresses doesn’t stack up, considering the terrain, lack of supplies and construction methodology lending them to easy assault.
    • The Dúns are not located at high points making them hard to defend against human attackers.
    • Contradiction between building some forts away from cliffs and some on cliffs leading to obvious conclusion that all were built away from cliffs prior to cliff creation.
    • Most of the entrances to the Dúns are on the E, NE or SE sides, indicating that wave attacks were expected from the W,NW or SW which is where we would expect the waves to come from.
    • There is a lack of mythological evidence linking the Dúns to historic battles and chiefdoms.
    • It is possible that the land was inundated at some time after the building of the last Dún. The land was therefore abandoned and folk memory concerning the Dúns was lost.
    • When the land resurfaced as the Aran Islands it was resettled again long after the original settlement and long after Tsunami waves had subsided. The Dúns may have been adopted by later rulers for different purposes. This would explain archaeological evidence found to date.
    • Irish Annals mention the legend of a violent shock tearing the Islands from neighbouring continent.
    • Could the effect of Eustasy and Hydro-isostasy competing against Glacial isostatic rebound have lead to the creation of the cliffs we see today? The land falling away became inundated and submerged as Eustatic sea levels continued to rise.
    • The ledgends of Hy-Brazil and  Atlantis support theories of former lands submerged. If the Dúns of Aran are evidence of Tsunami defences from six to eight thousand years ago they provide important indirect evidence for the occurrence of landslides and/or earthquakes in ancient times.