The Basin and Range pulls apart
Western North America stretches by hundreds of kilometres, breaking into parallel mountain blocks and valleys.
- When
- —
- Duration
- 12 million years
- Known to
- ± 2 million years
- Era
- Miocene, Cenozoic
From the early Miocene the crust between the Sierra Nevada and the Colorado Plateau extends dramatically, thinning and breaking along normal faults into a corrugated landscape of north-trending ranges separated by sediment-filled basins. Total extension amounts to roughly a doubling of the province's width. The cause is a combination of gravitational collapse of over-thickened crust and the growing influence of the Pacific-North America shear. It is the type example of continental extension, and its topography defines Nevada.