For example, to understand the topographic form and hydrologic systems that structure the Emerald Necklace park system, a student of the Olmsted firm's project must study more than the 1894 plan. That engraving depicts streets, water bodies, plantations of trees, and meadows, but no topography. The site appears flat. The shapes and locations of the various "beads" along the Necklace seem arbitrary-or informal and unstructured. After studying the landforms of the park system through grading plans of the period and contemporary U.S. Geological Survey (USGS) maps of Boston, one discerns repeated landforms, such as drumlins and eskers, that characterized this glaciated terrain. The alignment of the Necklace is not irregular; it maximizes the diversity of landscape types that characterize New England. The alignment of the Necklace and the undulations of the land within its boundaries speak of the structure of the land.