Synopsis: Rheological properties of earth materials play a crucial role in controlling the dynamics and evolution of our planet. Since materials in the solid earth are all under pressure, effects of pressure on the rheological properties are of central importance and have been studied by many researchers using various appraoches. In this talk, I would like to present an overview of the rheological studies at the GSECARS facilities at the Advanced Photon Source. A short background introduction will be followed by some technical description of the unique approaches taken at our facility. Scientific results will be given to provide a flavor of the kinds of research currently being conducted. Finally, future research directions and technical developments will be discussed, in order to expand to a wider range of areas pertinent to understanding the Earth.