Allarød gytja discovery proves climate oscillation. In 1901, Harts and Milthers discovered a 30cm (about 1 foot) thick gytja layer at Allerød, Denmark Gytja is dark, oxygen-rich mud rich in organic nutrients that forms in marshes and lakes The gytja layer was sandwiched between glacial clay deposits below and above

Harts and Milthers found a 30cm layer of gytja at Allerød, Denmark — sandwiched between glacial clay deposits. The gytja contained birch trees and juniper, proving milder conditions existed between two cold periods. This established the cold-warm-cold oscillation pattern we now call the Older and Younger Dryas.

Key Facts

  • In 1901, Harts and Milthers discovered a 30cm (about 1 foot) thick gytja layer at Allerød, Denmark
  • Gytja is dark, oxygen-rich mud rich in organic nutrients that forms in marshes and lakes
  • The gytja layer was sandwiched between glacial clay deposits below and above
  • The gytja indicated climate amelioration - it cannot form under full Arctic conditions
  • The flora in the gytja included birch trees and juniper, showing milder climate than the glacial clays
  • This discovery established the climate oscillation pattern: cold-warm-cold