Transport properties play a key role in the dynamics of the Earth. These properties bridge very different length- and time - scales. Microscopic mechanisms at the atomic scale involving crystal defects are ultimately responsible for large-scale processes on the plate tectonic scale. The time-scales of atomic jumps and vibrations are separated from those of orogenic processes they control by about 25 orders of magnitude. Spectacular developments in recent years in several areas are now enabling us to explore and understand these connections over such disparate scales. Analytical abilities make it possible to observe crystal defects (point defects, dislocations) and their motions with a clarity that was not possible until recently. Computational advances now allow us to connect these to transport processes (diffusion, plastic deformation). And finally, a combination of detailed geophysical (seismic tomography, satelliite based geodesy) and petrological observations combined with geodynamic modelling where time-scales are explicitly addressed elucidate how atomic scale processes control the large scale dynamics. This session wishes to bring together researchers from all of these diverse areas to explore the connection between defects and transport on all scales using experimental, analytical, computational or field based methods.