A Tapestry of Time and TerrainThis map weaves together, in vivid colors and shadings, the topographical and geological components of the lower 48 states, as well as the geologic age of those components. It outlines the geologic story of continental collision and break-up, mountain-building, river erosion and deposition, glaciation, volcanism and other events and processes that have shaped the region over the last 2.6 billion years. Includes descriptions of geologic times and selected features (e.g., the Llano Uplift in Central Texas and the Llano Estacado in the Texas Panhandle).