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Interesting YT Lecture about Formation of West Coast of North America

July 14, 2020 2 comments

Here is an interesting lecture by Nick Zentner of CWU (Central Washington University) about how the modern west coast states of USA (WA, OR and CA) and Canada (BC) were formed over past 100 million years. Long story short, they are Exotic Terranes which is a fancy way of saying that they were formed elsewhere, in most cases under oceans. The thing is.. most of the land which makes up these modern day states was formed under the ocean or as islands near the equator in the pacific. They then drifted towards the old coast of North America because of continental drift (specifically oceanic plate subduction) which fused these islands onto its western edge.

It is interesting to note that, based on current geological studies, more than a few waves of such oceanic islands ended up aggregating to the continent. He also touches on how land formed off the coast of present day mexico ended up moving to BC and WA (from ~90-55 mya) due to repeated earthquakes over about 35 million years along a now disappeared lateral-slip fault not unlike modern San Andreas fault. This is known as the Baja-BC hypothesis and while it was once seen as highly unlikely- it is now basically geological canon. There is also some mention of other contributors of this exotic terrane such as Siletzia and others.

What do you think? Comments?