EESA06H3 Chapter 20: Geological History of Canada
Document Summary
Canada: a young nation, but an old country. Began ~4000mya w/ formaion of acasta gneiss of northwest territories (nwt), which now forms part of slave province of canadian shield. Remains are fragments of superconinents that fused together b/c of plate tectonics. Formaion completed 65mya but landscape created by glaciaions in last 2. 5my. Northern part of coninent underlain by exposed part of ancient core (craton) called canadian shield. Consists of v. old, archean and proterozoic rocks: range from 4-1byo, largely devoid of fossils. Along w/ provinces, were ideniied by geologists in 19th cen. for mapping and recognized as terranes: discrete fragments of oceanic or coninental material added to craton @ acive margin by accreion. Originated as small coninents and remnants of ocean-loor crust and welded together to form craton. Outermost margins buried by layers of younger cover rocks (w/ thicknesses up to 10+ km) Largest in the world: extends from atlanic seaboard, w beneath rocky mountains, s to texas.
