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USGS Geology in the Parks

View of Earth, 255 million years ago Tmescale timebar 255 million years ago

Earth
255 million years ago

Permian

What's going on here?

  • The continental collisions that began in the Carboniferous (Mississippian) Period completed the work of assembling Europe, North and South America, Africa, Antarctica and other continents into the supercontinent Pangaea in the Permian Period. Pangaea was surrounded by subducting ocean plate on all sides. A single ocean, the Panthalassic, washed its shores.
  • The climatic and other environmental consequences of Pangaea's formation were extreme! Continental collisions built high mountains where lowland forests, swamps and coral reefs once flourished. Many of the world's shallow seas became isolated and dried up. Entire ecosystems were obliterated, resulting in massive extinctions.
  • High mountain chains blocked the flow of moisture-laden air across the supercontinent, creating a rain-shadow effect. The climate became increasingly arid. Desert conditions prevailed across much of the midcontinent.

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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