Kaushik “Crannogs: Neolithic-Era Artificial Islands”

以前、大竹昭子須賀敦子の旅路』を読んでいて、ヴェネツィアについての、「海中深いカラント層に、硬い材質の木を無数に打ち込み、その上に、イストリア半島産の石材を積み上げて、島の基礎はつくられた。それがなんと五世紀のことなのだ」という記述を読んだとき(p.152)*1、凄い! と思ったのだ。しかし、大規模ではなくても、水面を埋め立てて人工の陸地を作る技術は、アイルランドスコットランドにおいては、「新石器時代」まで遡るという。crannogとはそうした人工島。アイルランドでは1200箇所、スコットランドでは600箇所見つかっており、新石器時代に止まらず、中世に至るまで人が住んでいた形跡があるという。

The Irish word crannóg derives from Old Irish crannóc, which referred to a wooden structure or vessel, stemming from crann, which means "tree", plus a diminutive ending—literally "young tree". The modern sense of the term first appears sometime around the 12th century; its popularity spread in the medieval period along with the terms isle, ylle, inis, eilean or oileán. There is some confusion on what the term crannog originally referred to, as the structure atop the island or the island itself. The additional meanings of Irish crannóg can be variously related as 'structure/piece of wood', including 'crow's nest', 'pulpit', or 'driver's box on a coach'; 'vessel/box/chest' more generally; and 'wooden pin'. The Scottish Gaelic form is crannag and has the additional meanings of 'pulpit' and 'churn'. Thus there is no real consensus on what the term crannog actually implies, although the modern adoption in the English language broadly refers to a partially or completely artificial islet that saw use from the prehistoric to the Post-Medieval period in Ireland and Scotland.
See also

Scottish Crannog Centre “What is a Crannog?”
Erin Blakemore “Artificial islands older than Stonehenge stump scientists”