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:
“The English were very backward to explore and settle the continent which they had stumbled upon. The French preceded them both in their attempts to colonize the continent of North America ... and in their first permanent settlement ... And the right of possession, naturally enough, was the one which England mainly respected and recognized in the case of Spain, of Portugal, and also of France, from the time of Henry VII.”
—Henry David Thoreau (18171862)
“So motionless, she seemed stone deadjust seemed:
She was too old for death, too old for life,
For as if jealous of all living forms
She had lain there before bivalves began
To catacomb their shells on western mountains.”
—Edwin John Pratt (18821964)
“It is the sea that whitens the roof.
The sea drifts through the winter air.
It is the sea that the north wind makes.
The sea is in the falling snow.
This gloom is the darkness of the sea.”
—Wallace Stevens (18791955)
“In going to America one learns that poverty is not a necessary accompaniment to civilisation.”
—Oscar Wilde (18541900)