The faults in Arizona that cut Quaternary units are mainly up on the Colorado Plateau and roughly follow the egde of the plateau. There are a high concentration of faults in and around the Flagstaff volcanic area. In the above image I have highlighted in blue the faults which cut Quaternary age volcanics to give an idea of the concentration and distribution of active faulting in the region. Quaternary volcanism is located in the same general areas as the active faulting which cuts Quaternary units, indicating a link between active volcanics and active faulting in the Quaternary. There are also a few areas of isolated young volcanic units in the transition zone, as well as out in the basin and range region of the state. There is a distinct change in the location and distribution of volcanism between the Tertiary and the Quaternary. Tertiary volcanism is widespread throughout the basin and range and in the transition zone, whereas volcanism during the Quaternary is concentrated in three main regions on the Colorado Plateau. The loci of volcanism is moving NE through time.