What is the difference between base maps, themes, and thematic layers?
Base maps are background image tiles for the map. Your base map choices (the buttons on the top right of the map viewer) are Street, Satellite, or Hybrid. Themes are the spatial data content that overlay on top of the base map. Your theme choices are Conservation Priorities, Protected Areas, Threats, Plants and Animals, and Ecosystems (use the Select Theme button). Each theme automatically displays several thematic layers—different data sets relevant to that theme. For example, the Conservation Priorities theme includes a layer for Nature Conservancy ecoregional priorities, a layer for State Wildlife Action Plans, and layers for specific state-level plans. Thematic layers from any theme can be overlaid and viewed together using the Customize Theme button.
