The northern Cordillera, located on a continent-ocean interface in exi
stence for 750 million years, is an orogenic collage mostly made up of
Paleozoic through early Mesozoic intraoceanic are and subduction comp
lex terranes accreted to the craton margin, and mid-Mesozoic to Holoce
ne arcs emplaced mainly in and on the accreted terranes. Mountain buil
ding results from crustal thickening most likely caused by persistent
movement of the North American plate towards, and over, various Pacifi
c oceanic plates since Early Jurassic time. Location of collage compon
ents in time and space is needed to show the succession of plate confi
gurations that led to the collage, but current conflict between estima
tes of amounts of lateral displacements means that pre-Tertiary paleog
eographies remain in doubt.