All Earth systems evolve because — at a fundamental level — mass, energy and momentum associated with these systems are transported over space and exchanged among system components. Our research group examines transport processes that are important in a wide variety of Earth and environmental systems, focusing on how principles of conservation provide a unifying language that underlies both classic and emerging styles of analyzing how systems "work." We apply this unifying language to topics as varied as magma dynamics, nutrient transport and trophic interactions in rivers and estuaries, sediment and soil transport, and flow/reactions within porous media. In doing so, we discover numerous, delightful commonalities among these nominally disparate topics; and we nurture a style of thinking that is a cornerstone of "modeling" the behavior of Earth and environmental systems.