Life takes hold

Eighteen thousand years ago, glaciers covered almost the entire Canadian land mass, precluding any form of life. Then some fifteen thousand years ago, when the ice began to melt, species that had taken refuge farther south began the long reconquest of the land. The hardiest species followed the retreating ice front, preparing the way for the more tender species that followed behind them. Thus the existing mosaic of Canadian landscapes—the majestic cathedral forests of the cordillera, the dark boreal forests, the prairies and the swamps—were born of a slow maturation that took place over several thousand years. As to the present distribution of vegetation, it is thought to have been shaped in recent centuries by the climate, topography and soil conditions.