A forest drowned in place
On the mudflats of Yeongjongdo Island, a forest from 5,000 years ago appears and disappears with the tides. At low tide, the dark, slick mud reveals the remains of dozens of tree stumps, rooted in the exact positions where they grew during the Neolithic period. This is not a collection of driftwood, but an entire forest ecosystem that was submerged and preserved as sea levels rose during the mid-Holocene climatic optimum.
The stumps are the remains of a coastal forest that thrived when the shoreline of the Yellow Sea was much farther out. Around 5,000 years ago, as the last ice sheets of the Pleistocene melted, global sea levels rose. The encroaching salt water inundated this forest, killing the trees. The waterlogged, oxygen-poor mud then encased the lower trunks and root systems, preventing decomposition and preserving them for millennia. Analysis of wood from similar prehistoric sites in Korea shows that oak species (Quercus spp.) were dominant in the region's ancient forests.
A record of rapid change
The Yeongjongdo Fossil Mudflat Forest is a direct physical record of past climate change and its effect on coastal geography. The existence of the forest provides a precise data point for mapping the ancient coastline. The death of the trees, in turn, offers a timestamp for when the sea reached this exact location. Scientists use such "drowned forests" around the world to reconstruct the rate and magnitude of past sea-level changes.
The stumps stand as a silent chronicle of an environment in transition. Their preservation in their growth positions—or in situ—is what makes the site scientifically valuable. It allows for the study of the ancient forest's density and structure. Pollen and other microfossils trapped in the surrounding sediment layers can also show details about the wider plant and animal communities that existed here before the land was claimed by the sea. The site provides a clear picture of how dramatically and quickly a environment can be transformed by shifts in global climate.