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. |
Famous quotes containing the words north america, western, north and/or america:
“Civilization does not engross all the virtues of humanity: she has not even her full share of them. They flourish in greater abundance and attain greater strength among many barbarous people. The hospitality of the wild Arab, the courage of the North American Indian, and the faithful friendships of some of the Polynesian nations, far surpass any thing of a similar kind among the polished communities of Europe.”
—Herman Melville (1819–1891)
“It appeared that he had once represented his tribe at Augusta, and also once at Washington, where he had met some Western chiefs. He had been consulted at Augusta, and gave advice, which he said was followed, respecting the eastern boundary of Maine, as determined by highlands and streams, at the time of the difficulties on that side. He was employed with the surveyors on the line. Also he called on Daniel Webster in Boston, at the time of his Bunker Hill oration.”
—Henry David Thoreau (1817–1862)
“We might hypothetically possess ourselves of every technological resource on the North American continent, but as long as our language is inadequate, our vision remains formless, our thinking and feeling are still running in the old cycles, our process may be “revolutionary” but not transformative.”
—Adrienne Rich (b. 1929)
“No culture on earth outside of mid-century suburban America has ever deployed one woman per child without simultaneously assigning her such major productive activities as weaving, farming, gathering, temple maintenance, and tent-building. The reason is that full-time, one-on-one child-raising is not good for women or children.”
—Barbara Ehrenreich (b. 1941)