When Did the Farallon Plate Start Subducting?

At the beginning of the sequence 50 million years ago, the Farallon plate was sinking under the North American continent, pushing into it and building mountain ranges such as the Rocky Mountains. The Farallon plate was subducting as a coherent plate along the entire length of North America from Alaska down past Mexico.

When did Farallon plate subduction?

Farallon Plate subduction forms North American Cordillera

In April 2013 Sigloch and Mihalynuk noted that under North America these subducting slabs formed massive, essentially vertical walls of 800 km to 2,000 km deep and 400–600 km wide, forming "slab walls".

When did the Farallon plate begin subducting under the North American plate?

Many millions of years ago, the Farallon plate subducted beneath the entire west coast of North America. Approximately 30 million years ago, the mid-ocean ridge that created the Farallon impinged on the subduction zone near where Los Angeles is today, and the Farallon began its death march both northward and southward.