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USGS Geology in the Parks

View of Earth, 390 million years ago Tmescale timebar 390 million years ago

390 million years ago


What's going on here?

  • By 390 million years ago the supercontinent Gondwana and the newly-welded 'Euramerica' were surrounded by subduction zones on all sides! Most of the continental land masses were bunched-up; a vast ocean, covered the rest of the planet.

    Keep your eye on Gondwana. With the development of the subduction zone between Gondwana and Euramerica a collision course is set that will culminate in the formation of a single supercontinent, Pangaea.

    Here's how to keep track of what's going on: See the orange line of 'teeth' that marks the subduction zone between Gondwana and Euramerica? The Euramerica plate, the side with the pointy ends of the teeth, is the more buoyant plate. The Gondwana side is sinking beneath Euramerica right along the subduction zone. Gondwana is gradually being pulled toward the Euramerica. As you can see, when the continental crust of the Gondwana plate hits the subduction zone, collisions on an unimaginable scale will be the inevitable result!
  • As you can see, the pattern of repeated continental flooding, followed by receding seas that began in the Cambrian continued through the Devonian Period.

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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