Tectonic Evolution of Western North America |
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| ca. 25 - 10 MYA |
| The Sierra Nevada remained tilted westward as North America continued west over mantle upwelling of the Pacific Spreading Center. No longer dragged downward by the subducting Farallon Plate, the edge of North America rebounded isostatically, lifting the Coast Ranges. As thinner crust east of the Sierra Nevada passed over the zone of upwelling mantle, the crust broke into north-trending blocks. |