How do basin and range mountains and valleys form?
The basins (valleys) and ranges (mountains) are being created by ongoing tension in the region, pulling in an east-west direction. Over most of the last 30 million years, movement of hot mantle beneath the region caused the surface to dome up and then partially collapse under its own weight, as it pulled apart. If it continues to pull apart, it could create a spreading ridge with an intervening ocean. Currently, there is very little actual stretching going on, and the small amount is concentrated on the western and eastern edges of the Basin-Range.
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Basin & Range province
- Created by tension as the land is being pulled apart during uplift
- Parallel normal faults are a signature for basin-range extension
- The plate stretches, fractures, and thins
- Mountains rise, valleys drop during faulting