England and Scotland: Always Part of the Same Island (Great Britain)

England and Scotland have never been separate islands. Both are on the island of Great Britain, which also includes Wales. The Anglo-Scottish border is a land boundary established by treaty (1237, 1603 Union of Crowns, 1707 Acts of Union). Geological history: the Iapetus Ocean closed ~420 Ma, suturing the Laurentian (Scotland) and Avalonian (England) terranes—long before humans existed.