The Superior Province is the heart of the continent.
It is ringed by additions which were welded to it along "collisional
belts," among them the Grenville Province and the Trans-Hudson
Orogen. In a moment, we shall look at how such collisions occur.
Like the Superior Province, the Hearne-Rae, Slave, and Nain Provinces
are of Archean age.
The Appalachians and Cordillera, on the other hand, are the most
recent additions to our continent, which occurred during the Phanerozoic.
That is the last big chapter in our planet's history, remember,
when Earth already was alive with many forms of advanced life, some
small fraction of which we now find preserved in fossils.
Let's refresh our memory and go back to the geological time table
we saw earlier.