Curvature of structural trends in mountain belts may occur in several ways. The original geometry of the convergent plate margin may be irregular, or a collision with a relatively rigid block may cause an indentation. I propose that rapid sedimentation may be as effective as a rigid indenter in creating locally curved structural trends within the upper plate. This mechanism is active on the northern Colombian convergent margin where the Magdalena fan is being deposited on the upper plate as well as on the subducting Caribbean plate. The structural response has been indentation and curvature of the accretionary wedge and increased deformation inboard of the Magdalena fan, increasing the tectonically driven uplift of the Santa Marta block in Colombia.