Climatic control of continental physiography

The spatial distribution of elevations and slopes on continents is a primary expression of complex interactions between tectonic and climatic systems. Because rates of tectonism and climatically mediated erosion vary in both space and time, it is possible that heights of land and steepness of associated slopes change both across climatic regimes and during the tectonic evolution of any particular landmass. As a geomorphic record, spatial variations of continental physiography with latitude afford some insight into the relative importance of tectonic and climatic processes in controlling Earth surface elevations. Because modern digital elevation models afford abundant data on continent surfaces across the complete set of equator to pole climate ranges, we have undertaken an evaluation of the dependence of continental physiography on climate using the latitudinal gradient as a proxy for first-order change in temperature and precipitation. Continental hypsometries can be largely explained by elevation distributed as an exponential function of the square root of area of land, and hypsometries with normalized maximum elevations and total areas exhibit no significant latitudinal variation. This suggests that spatial variation in Earth surface topography, as manifest by area-elevation relations, is largely insensitive to latitudinal position and associated climate. Land surface slope, however, does covary with absolute latitude. Steeper slopes are apparent at higher latitudes and likely record the poleward influence of cryogenically mediated processes of continental denudation. The coincidence of increasing subaerial slopes with latitude and stasis in hypsometric distributions of elevations suggests that poleward regions are also more dissected than their equatorial counterparts.