A timeline of significant geological events in the evolution of western North America. Dates are approximate. ("Ma" = millions of years ago)
| Date | Period/Epoch | Event |
|---|---|---|
| 350 Ma | Devonian | An unnamed terrane collides and accretes to the North American Plate, along a line roughly coinciding with the Nevada–Utah border and called the Carlin Unconformity. |
| 250 Ma | Permian | The Sonomia Terrane collides and accretes to the North American Plate, along a line called the Golconda Thrust (also the name of the event) which runs through central Nevada. |
| 200 Ma | Triassic | Sierra Nevada batholith first develops. |
| 180 Ma | Jurassic | The Intermontane Plate collides with the Pacific Northwest, the remnants of which form the Intermontane Belt today. |
| 165 Ma | Jurassic | The Smartville Block, an island arc terrane, collides and accretes to the North American Plate, along a line which coincides with the Mother Lode country of California. |
| 140 Ma | Jurassic | Second wave of plutons added to Sierra batholith. |
| 115 Ma | Cretaceous | The Insular Plate collides with the Pacific Northwest. The remnants of that terrane comprise the Insular Belt today, of which Vancouver Island is a part. |
| 90 Ma | Cretaceous | Third and last wave of plutons added to Sierra batholith. |
| 43 Ma | Eocene | The Pacific Plate changes its direction of motion from north to northwest. |
| 35 Ma | Eocene | Rio Grande Rift begins to form. |
| 20 Ma | Miocene | San Andreas Fault comes into being as the North American Plate begins splitting the Farallon Plate in two. |
| 17 Ma - 14 Ma | Miocene | Columbia River Basalt Group Forms. |
| 8 Ma | Miocene | Onset of faulting creating the Basin and Range geologic province. |
| 5 Ma | Miocene - Pliocene | Northward propagation of the East Pacific Rise into the North American Plate initiates rifting off of the Baja California peninsula. |
| 4 Ma | Pliocene | Sierra Nevada begins to rise. |
| 3.5 Ma | Pliocene | The Pacific Plate changes its direction of motion about 11 degrees east of its previous heading, from northwest to the present northwest by north. |
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