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USGS Geology in the Parks

Earth during middle Eocene 50.2 Ma Geologic time scale Timescale

50.2 million years ago

What's going on here?

  • India has collided with Eurasia, raising the Himalayas and Tibetan Plateau.
  • Although remaining an active convergent boundary, western North America is relatively tectonically quiet during this time.
  • Find Baltica. By 458 million years ago, a subduction zone formed near the edge of Laurentia (North America's core). Baltica, made up of Scandinavia and part of the former USSR, was gradually being rafted along on the subducting plate toward North America.
  • New England was still far to the south, attached to what eventually becomes England. Now, I ask you, why is one "New England" and the other just plain "England"?

Reconstructing ancient Earth

These remarkable figures are produced by C.R. Scotese and the PALEOMAP project. Geologists call these illustrations paleogeographic reconstructions, because they illustrate the reconstructed geography of our Earth at some time in the past.

Making a paleogeographic reconstruction begins by examining several lines of evidence including: paleomagnetism, magnetic anomalies, paleobiogeography, paleoclimatology, and geologic history. By combining all available evidence, geologists are able to construct paleogeographic maps, such as these, that interpret how the geography might have appeared at a specific location and time in the past. Paleogeographic maps are continually being refined as more evidence is collected.

To find out more about how paleogeographic reconstructions are made visit the PALEOMAP project site.

Move forward or back in time.
| Today | 0.018 | 14 | 50 | 69 | 94 | 152 | 195 | 237 | 255 | 306 | 356 | 390 | 425 | 458 | 514 | 650 |
Time in millions of years. Jump back to visit any time!

Scotese, C. R., 1997. Paleogeographic Atlas, PALEOMAP Progress Report 90-0497, Department of Geology, University of Texas at Arlington, Arlington, Texas, 37 pp.

| Into Earth | | Putting the pieces toge ther | | Action at the edges |
| National Parks by Tectonic Regions |
| Earth through time | | Detailed version: This Dynamic Earth |


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