快猫短视频

ANCIENT sooty layers buried deep within the thatched roofs of historic
buildings can preserve a perfect record of the plants that grew in medieval
fields. But thatchers are now discarding this unique material.

In a new report commissioned by English Heritage, the agency responsible for
conserving historic buildings, John Letts of the University of Reading describes
how dry thatch buried under as much as 2 metres of later material is protected
from insect and fungal attack by soot and tar from fires.

鈥淭his smoke-blackened material is often perfectly preserved with fingerprint
quality DNA,鈥� he says. 鈥淚f you鈥檙e used to working with half-decayed samples from
archaeological digs, it鈥檚 amazing to see all the varieties of cereal and the
weeds they grew with exactly as they were taken from the field.鈥�

Of the 325 known buildings with smoke-blackened thatch, 300 are in Devon.
Letts says that Devon鈥檚 thatchers attached battens to rafters with wooden pegs,
which have lasted better than the iron nails used elsewhere. This meant that the
lower layers of thatch never needed to be replaced.

But Letts warns that this research resource could be lost as commercial
thatching companies adopt new methods. Rather than attach thatch to existing
base coats, they prefer to throw away the original material and nail new
thatching鈥攗sually water reed rather than the traditional wheat
straw鈥攄irectly to the rafters.