MIT Libraries logo

Search Constraints

Number of results to display per page

Search Results

1. Omernik's Level III Ecoregions of the Continental United States, 2003

2003. United States. Environmental Protection Agency. This polygon shapefile shows Omernik's Level III ecoregions, derived from a 1:7,500,000 map created by J.M. Omernik in 1987 and from refinements of... National Atlas of the United States.