Final answer:
The destruction of plant life around Mont Pelée in 1792 and 1851 was due to superhot pyroclastic flows, which are destructive currents of hot gas and volcanic matter from a volcanic eruption.
Step-by-step explanation:
The destruction of plant life around Mont Pelée in 1792 and 1851 was caused by superhot pyroclastic flows. A pyroclastic flow is a fast-moving current of hot gas and volcanic matter that moves away from a volcano reaching speeds of up to 700 km/h (430 mph).
It is capable of destroying nearly anything in its path due to its extreme temperature and speed. The descriptions provided align with typical indicators of volcanic eruptions, such as the explosive eruption of Mount Vesuvius, the dramatic impacts of Mount St. Helens, and the preservation of organic material at Herculaneum by pyroclastic flows.
Such destructive events can dramatically alter the landscape and devastate any nearby ecosystems, including the destruction of forests as seen at Mount St. Helens, and the petrification of organic material as happened in Herculaneum.