THE NORTH AMERICA TAPESTRY OF TIME AND TERRAIN

The North America Tapestry of Time and Terrain (1:8,000,000 scale) is a product of the US Geological Survey in the I-map series, to be published later this year. The map was prepared in collaboration with the Geological Survey of Canada and the Mexican Consejo Recursos de Minerales.

This Tapestry is woven from a geologic map and a shaded relief map. The combination reveals the geologic history of North America through the relationship among geology, topography and time. Regional surficial processes as well as continental-scale tectonic events are exposed in the three dimensions of space and the fourth dimension, geologic time.

The main map shows the age of the bedrock underlying North America, while four smaller maps show the distribution of four principal rock types: sedimentary, volcanic, plutonic and metamorphic.

The geologic data were generalized from the forthcoming Decade of North American Geology Geologic Map of North America compiled by John C. Reed (USGS) and John O. Wheeler (Geological Survey of Canada), sponsored by the Geological Society of America. Processing and reprojection of the geologic data were done in ArcINFO GIS. The underlying cartographic structure is a shaded relief map derived from a 1-kilometer digital elevation model (DEM). John Hutchinson (EROS Data Center) supplied the original DEM. The projection used is Lambert Azimuthal Equal Area. The two component maps were georeferenced to one another using GIS software and the final images were combined using graphics software.

This map is an extension of the 2000 Tapestry of Time and Terrain by José F. Vigil, Richard J. Pike and David G. Howell, which covered only the conterminous United States. The U.S. Tapestry poster and website have been popular in classrooms, homes, and even the Google office building, and we anticipate the North America Tapestry will have a similarly wide appeal, and to a larger audience.