The deposits are lake sediment, and are of uncertain age.

The fenced-off area was then layered with mud, lake sediment, and decaying vegetation, eventually bringing it above the level of the lake.

Subsidence of the caldera through time has been partly offset by the deposition of tephra, lava flows, and lake sediment.

The valley floor owes its flatness to sediment deposited by these stands (the last glaciers in the valley were small and did not remove much old lake sediment).

Ecological toxicity testing found that lake sediments were toxic to aquatic life.