Lecture 1: Lithosphere, Asthenosphere and Archimedes

Slide 14 of 20

The picture on the right shows that mantle plumes (yellow/red) initiate at the core/mantle boundary. The warm material of the plumes is replaced by cold lithospheric material (blue). The movie presented below will help you to visualise the dynamic of that process.
This animation from Brigit Schroeder, David A. Yuen, and Zhou Hua shows the development of flush instabilities at the asthenosphere/mesosphere boundary. It also shows slab retrograde motions at the very surface of the Earth, and the relationship between flush instabilities and plume formation in the lower mantle. For more: http://banzai.msi.umn.edu/	Click on the picture to see the movie.