The central area was land
The dark brown section is peat, which forms in wetland areas on land.
The layers above and below the peat are thought to have been deposited in a lagoon or the sea, indicating that the presence of peat here suggests this area was once land.
This is estimated to have occurred around 4,000 years ago.
[Block Sample]
It is peat, formed from plants such as grasses and mosses that grew in wetlands.
As these plants died, they accumulated layer by layer, and instead of fully decomposing, they remained preserved.
