The rocks in the asthenosphere are not rigid, but are semi-plastic in nature. They are more like clay, as the temperature in the layer is very close to their melting point.
The asthenosphere is responsible for the movement of the lithosphere, the layer of solid rock above it. The rocks float on the semi-dense layer below it. This motion causes plate tectonics: the slow movement in the earth´s crust that is the cause of earthquakes, volcanoes and continental drift.Learn more about Atmosphere