Source: Coney 1976. Click to enlarge.
The Laramide orogeny was produced by the dynamics of moving plates and possible complex interactions between North America and one or more "Pacific plates" to the west (Coney 1976). Subduction of the Farallon Plate beneath the North American plate led to the formation of the North American Cordillera. When the subducting Farallon plate began to flatten, the magmatic arc shifted eastward.
Source: Maxson and Tikoff 1996.
Source: Perry and Flores 1997.
Source: Brown 1988.
Source: Bird 1998.
On to Tectonics: Flat Subduction