What is the asthenosphere made of?

As part of the earth's upper mantle, the asthenosphere is thought to contain rock material made from peridotite, eclogite, olivine, spinel, garnet and pyroxene. The asthenosphere is about 50 to 124 miles beneath the earth's surface, and it is described as viscous, meaning it can move and flow, and plastic, meaning it responds to deformation.

Though it is plastic and viscous, the asthenosphere is actually made of solid rock rather than liquid magma. The asthenosphere's mechanical properties, or texture, can be compared to that of silly putty and other soft solids that are easily malleable, which is a contrast from that of the lithosphere, the layer directly above the asthenosphere.