In 1973, broken rocks, large pieces of cement, and concrete rubble tumbled and crashed down from the dump truck with banging thunders and billows of dust to begin the building of a dike along Green Bay, Wisconsin. This dike was typical of those composed of riprap to prevent future erosion and ﬂooding. Riprap is human-made and used in many places to protect roads, bluffs, bridges, and shorelines from the erosion caused by wave action and to bolster structures threatened in other ways. Riprap also refers to rocks laid down on a smooth stone path to provide traction for horses on the slippery surface. “Lay down these words/ Before your mind like rocks,” Gary Snyder suggests in his poem “Riprap,” comparing the granite words of a poem to the bolstering aggregation of riprap.