The geometry of foreland basins is controlled by a dynamic balance between thrust-belt migration, flexural subsidence, and fluvial deposition. To improve our ability to quantify the relationships between tectonics, climate, and foreland basin geometry, I developed analytic solutions for basin topography and stratigraphy using a classic two-dimensional mathematical model of foreland basin evolution. Model predictions for basin topography are successfully tested against observed profiles along a humid-to-arid climatic gradient in the central Andes. Using published estimates for the thrust-belt migration rate, flexural parameter, and thrust-front basin depth in this region, I show that basin topographic profiles can be used to estimate the upstream erosion rate at any point along a foreland basin. Basin-averaged erosion rates estimated in this way vary from 0.025 to 0.045 mm/yr in the central Andes, increasing from semiarid to humid climates.