Topographic relief on the Earth's surface is continually modified by tectonics, erosion, and deposition. Local effects of the interplay of external and internal processes and biology are well known to geologists. Local relief on land is often the result of differential erodability of various exposed rock types. Increased rainfall on the windward sides of mountain ranges leads to intense runoff and rapid erosion. This ``orographic precipitation'' effect results in two-way coupling between climate and tectonics within compressional orogenies, including those associated with arc-continent collisions, continent-continent collisions, thrust belts landward of subduction zones, and regions of ``transpression'' where a component of crustal convergence exists across mainly strike-slip systems. Some surficial influences on compressional orogens are well known. The thickness of sedimentary rocks present determines the amount of material available for accretionary wedges and thin-skinned tectonics. Differences in mechanical properties between sedimentary beds lead to buckling and to the development of layers, called decollements, where sliding occurs easily. It has recently become evident that a complex two-way interplay between tectonics and climate greatly influences the development of mountain ranges and thick-skinned basement structures in compressional orogens.