Photo: Дар Ветер · CC BY-SA 3.0 · via Wikimedia Commons
Mud Flood · Veliky Novgorod, Russia
Novgorod cultural layer
The open question
Metres of ground built up under a city in a few centuries. Is that all rubbish and rebuilding, or did something else bring it?
On the record
Novgorod's historic centre has a deep, wet 'cultural layer' of built-up ground from the 11th century on, which has preserved about 1,000 birch-bark letters.

