R.L. wrote:
But isnt it safe to say that tectonics MUST have existed in its early history? Such evidence may be buried deep, I was just wondering is more recent features showed any evidence of geologically (say past few hundred million years) recent motion...

Alex writes:
As Nick noted, most of the Mars science community believes that Mars has been been a single plate planet at least all the way back to the Lower Noachian. Local/regional compressional or extensional faulting (e.g., due to the load imposed by Tharsis) is tectonic activity, but the only real evidence for terrestrial-type plate tectonics is the magnetic striping discovered by MGS MAG/ER. Mind you, these data are only suggestive, certainly not compelling. Moreover, other workers dispute this interpretation and have countered with other explanations that are just as plausible (e.g., intrusion dikes). That said, however, plate tectonics does remain a viable mechanism. The only drawback is that if this is true, then the stratigraphic relationships (i.e., Hellas apparently postdates the striping) suggests that any plate tectonics shut down very early, probably pre-Noachian in conjunction with the (probable) cessation of the geodynamo.

Alex R. Blackwell
University of Hawaii