The Middle Sea and the Marne
 The old sea clay region in Friesland used to be divided in half by a large inlet, the Middle Sea. This inlet formed in 3 AD, when seawater overpowered the peat bogs. In the year 500, the sea inlet Marne reached the Middle Sea, isolatingg Westergo. The Marne and the Middle Sea silted up after the Zuiderzee formed. Due to various land reclamations between 1000 and 1800, the Nieuwlanden and the Bildt were formed. Leeuwarden, once a settlement on sea, became an inland city. |
Formation of the Middle Sea
Around 1000 B.C., a thick layer of peat bog lay where the Middle Sea would later form. The Boorne, a river which is still flows by Akkrum, discharged into the sea. A border of dunes protected the land, but the sea penetrated inland via channels. It deposited clay onto the bog, creating wide marsh walls. The marsh wall with the clay-covered bog regions laying beyond attracted inhabitants. In order to be more assured of dry land for their cattle, the occupants dug a network of ditches. This dehydrated the bog, causing it to settle. Exposure to oxygen in the air caused extra erosion of the bog, which decreased the available liveable area. In the year 3 A.D., the sea water again penetrated inland and as the Boorne broadened in the following centuries, the Middle Sea formed.
The Marne
The Marne was also a sea inlet, just like the Middle Sea. It lay in the extension of the present channel between Harlingen and Terschelling. Around 500 A.D., the Marne made contact with the younger Middle Sea, cutting cut off Westergo from the rest of Friesland. More bog eroded away and Westergo became an island around 700 A.D.
Source: de Vleet, Ecomare
