There was a unique development at Durocornovium in the 4th century. Whilst it is possible that conventional stone buildings continued to be used, there was a proliferation of wooden buildings built on top of sarsen stone pilings to stay above ground level, a feature that explains the relative bounty of coins dating from that time as coins were dropped and lost through the floorboards. Such a change in architecture reflects what archaeologists believe was an increase in local flooding. It might also reflect changes in the economy and the availability of skilled trades.