Mud flows consisted of volcanic ash and rock, and organic debris occurred minutes after the eruption. Water levels in the river reached at least 4m above flood stage. Though the landscape produced by the landslide deposits is still there, it is a grim reminder of the eruption. Deforestation Forests cover much of the planet s land area. They are extremely important to humans and the natural world.
Trees protect the soil against erosion and reduce the risks of landslides and avalanches.
They may increase the rate that rainwater recharges groundwater as well as control the rate that water is released in watersheds. Forests affect the climate and are an important source of oxygen, although they play a lesser role than was once thought. Tropical rainforests may contain over one-half the world s total species. Today, however, mankind threatens the forests that provide so much. Since so many are dependent on the world s forests, deforestation will have many social, economic and ecological changes.