Large-scale continental extension significantly rearranged the distribution of pre-Tertiary rocks in southern and western Arizona during Miocene time [Spencer and Reynolds, 1989a]. Topography resulting from this extension event has been modified by subsequent less intense extension, and together these events are responsible for the physiographic division of the state into a three provinces: Colorado Plateau, Transition zone and Basin and Range. Rocks on the Colorado Plateau have been relatively unaffected by Phanerozoic deformation. The Transition zone has been affected by relatively weak Laramide deformation, and mildly to moderately affected by late Cenozoic normal faulting and basin and range topographic development. Basins are relatively shallow and little tilting accompanied the extension. The Basin and Range province has been affected by intense deformation during several episodes in Mesozoic time and large-scale extension, commonly accompanied by steep tilting of rocks, mostly during early to middle Miocene time. This project represents an initial attempt to produce a palinspastic map representing the distribution of rocks in early Oligocene time before extension. This map is intended to help analyze Laramide deformation and possible controls on the distribution of Laramide porphyry copper deposits. Preliminary reconstruction of Miocene Extension in the Basin and Range of Arizona and adjacent areas - with report and map, map scale 1:1,000,000.