The map above shows the ages of bedrock in North America from yellow (youngest) to green to blue to red (oldest). The maps official name is the The North America Tapestry of Time and Terrain.
It was created by Kate E. Barton, David G. Howell, José F. Vigil on behalf of the the U.S. Geological Survey in collaboration with the Geological Survey of Canada and the Mexican Consejo Recursos de Minerales.
Here’s the geologic timescales:
So even yellow bedrock may be 66 million years old, whereas the oldest could be over 4 billion years old!
From the abstract:
This cartographic Tapestry is woven from a geologic map and a shaded relief image. This digital combination reveals the geologic history of North America through the interrelation of rock type, topography and time. Regional surface processes as well as continent-scale tectonic events are exposed in the three dimensions of space and the fourth dimension, geologic time. The large map shows the varying age of bedrock underlying North America, while four smaller maps show the distribution of four principal types of rock: sedimentary, volcanic, plutonic and metamorphic.
You can sometimes buy a copy from Amazon here.
For more see:
- Interpretation of Geological Maps
- Essentials of Geology
- National Geographic Pocket Guide to Rocks and Minerals of North America
- 101 American Geo-Sites You’ve Gotta See
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