What caused the wood from ancient forests to be buried, leading to coal formation?

The formation of coal from ancient forests is primarily attributed to the processes that led to the burial of plant material. Flooding that prevents oxidation is essential in this context because when vegetation, such as trees and plants, dies, it must be rapidly buried by sediment to prevent decay through oxidation. This is typically achieved through water saturation, such as in swampy or flood-prone areas where plant material can accumulate over time.

When ancient forests were covered by water due to flooding, the lack of oxygen in the waterlogged environment inhibited the decomposition of the organic matter. As layers of sediment piled on top, the pressure and heat from the overlying materials transformed the dead vegetation into coal through a series of chemical and physical changes.

On the other hand, other options such as rapid deforestation would not lead to coal formation; rather, it would decrease the amount of plant matter available. Extreme temperatures alone are not sufficient for the transformation of plant material into coal without the important factor of anoxic conditions provided by burial. Similarly, an invasion of herbivorous animals would contribute to the consumption of vegetation rather than its preservation and burial, making it less relevant to the process of coal formation.