A scientist from Scottish Natural Heritage has confirmed the existence of the 6,500-year-old forest in Otterswick (Sanday, Orkney Islands, Scotland) and pinpointed its location. The 50-acre prehistoric forest on the west side of Otterswick Bay was first noted in the mid-nineteenth century, after a storm exposed moss with tree roots sticking out of the sand at low tide.
     The forest was first investigated in March 1850, and appeared on a hydrographic chart of the North Ronaldsay Firth, surveyed in 1847-48. It marks the site of the "Submarine Forest" between Lamaness Skerry and Helliehow. In 1867, in his History of Orkney, the Rev George Barry wrote: "There is a general and strong tradition that the harbour of Otterswick in Sanday was once a forest, which was destroyed by inundation." Despite the references, however, until now no one had actually recorded exactly where it lay.
Geomorphologist Alistair Rennie discovered the remains while studying the effect of rising sea levels in Sanday. Funded by Scottish Natural Heritage and Glasgow University, the investigation became aware of a number of local traditions that referred to a sunken forest in Otterswick. An 1847 map produced by one Commander Becker also had a submerged forest marked on it. So knowing roughly where to look, test digs were made in the bay at low tide.
     Lying beneath 75cm of sand and 10-15cm of shell fragments, the excavation revealed a 10-15cm layer of peat along with tree branches. Beneath the layer of vegetation was a thin layer of till on top of weathered bedrock. Twelve tree samples were removed and transferred to Glasgow for identification. Carbon dating revealed the trees to be 6,500 years old - in other words the forest had flourished around 4,500 BCE, about 1,300 years before the first settlement at Skara Brae. The discovery has shown that the sea level has risen by three metres over the subsequent centuries - an estimated rate of 1-3mm a year.

Source: Orkneyjar (9 September 2004)