This helpful teaching tool from the United States Geological Survey brings together the comprehensive geological and topographical maps of the United States. As the site suggests, "... this digital tapestry outlines the geologic story of continental collision and break-up, mountain-building, river erosion and deposition, ice-cap glaciation, volcanism, and other events and processes that have shaped the region over the last 2.6 billion years." First-time users will want to watch the Quick-Time film that shows the merging of the two maps, along with a brief description of how each individual map portrays the United States. Within the features description section of the site, visitors can interact with a clickable map surface that details the prominent features of the United States, such as the Driftless Area of southwestern Wisconsin and the Olympic Peninsula in the state of Washington. Equally helpful for learning about geologic time is the interactive map legend that allows users to learn about the different eras, like the Paleozoic or the Precambrian. For people who are looking to learn more about geology, this Web site will be one they will want to peruse several times.