The most striking signs of past eruptions are the lava flows that creep down the side of the volcanoes.
During an eruption streams of molten lava pour out of the sides and top of the volcano.
This lava solidifies as it cools, retaining its rippled texture from when it was in a liquid state.
Those volcanoes which have smooth sides indicate that there has been a recent eruption.
This happens because the erupting volcano fills the surrounding uneven surfaces with a blanket of lava and ash.
In contrast, areas that haven’t experienced recent volcanic activity are scarred by millions of years of erosion, mostly from water.
This results in creation of deep water-carved canyons and ravines which radiate from the summit of the volcano.
The heavy erosion on the sides of the volcano can also be attributed to Chad’s changing climate over the last two million years.
During wetter climates, high levels of rainfall added to the massive erosive powers of the streams and rivers in the Massif.