The character of convergence along the Arabian-Iranian plate boundary changes radically eastward from the Zagros ranges to the Makran region. This appears to be due to collision of continental crust on the west in contrast to subduction of oceanic crust on the east. The Makran ranges display progressively older and more highly deformed sedimentary units northward from the coast, together with an increase in elevation of the ranges. North of the Makran ranges are large subsiding basins, flanked to the north by active volcanoes. Published geologic data as well as Landsat images indicate that the Makran is a large sedimentary prism accreted during the Cenozoic. Almost all the characteristics of accretionary prisms observed in well-studied arcs can be identified or inferred in the Makran, which, however, is unique in its degree of exposure. These circumstances lead to a better understanding of Makran geology and of the mechanics of island arcs hi general.