Editing Coast Mountains (section)

====Insular and Omineca Arc eruptive periods====
[[Image:Insular Omineca arcs.png|thumb|right|Bridge River Ocean between North America and the Insular Islands]]
{{Main|Insular Islands|Omineca Arc}}
The first event began 130 million years ago when a group of active volcanic islands approached a pre-existing [[continental margin]] and coastline of North America.<ref name="AD">{{cite web|publisher=Burke Museum of Natural History and Culture|url=http://www.washington.edu/burkemuseum/geo_history_wa/Coast%20Range%20Episode.htm |title=The Coast Range Episode (115 to 57 million years ago)|access-date=2008-04-09}}</ref> These volcanic islands, known as the [[Insular Islands]] by geoscientists, were formed on a pre-existing [[plate tectonics|tectonic plate]] called the [[Insular Plate]] by [[subduction]] of the former [[Farallon Plate]] to the west during the early [[Paleozoic]] era.<ref name="AD"/> This subduction zone records another subduction zone to the east under an ancient [[ocean basin]] between the Insular Islands and the former continental margin of North America called the [[Bridge River Ocean]].<ref name="AD"/> This arrangement of two parallel subduction zones is unusual in that very few twin subduction zones exist on Earth; the [[Philippine Mobile Belt]] off the southeastern coast of [[Asia]] is an example of a modern twin subduction zone.<ref name="AD"/> As the Insular Plate drew closer to the pre-existing continental margin by ongoing subduction under the Bridge River Ocean, the Insular Islands drew closer to the former continental margin and coastline of western North America, supporting a pre-existing volcanic arc on the former continental margin of North America called the [[Omineca Arc]].<ref name="AD"/> As the [[North American Plate]] drifted west and the Insular Plate drifted east to the old continental margin of western North America, the Bridge River Ocean eventually closed by ongoing subduction under the Bridge River Ocean.<ref name="AD"/> This subduction zone eventually jammed and shut down completely 115 million years ago, ending the Omineca Arc and the Insular Islands collided, forming the [[Insular Belt]].<ref name="AD"/> Compression resulting from this collision crushed, fractured and [[fold (geology)|folded]] rocks along the old continental margin.<ref name="AD"/> The Insular Belt then welded onto the pre-existing continental margin by magma that eventually cooled to create a large mass of [[igneous rock]], creating a new continental margin.<ref name="AD"/> This large mass of igneous rock is the largest [[granite]] outcropping in North America.<ref name="AD"/>

[[Image:Coast_Range_Arc_tectonics.png|thumb|left|Plate tectonics of the Coast Range Arc about 100 million years ago]]