Built by a geologist

Plate Tectonics & Canada

Plate Tectonics & Canada Canada as we know it today was assembled over billions of years through the collision, accretion, and rifting of ancient microcontinents and terranes. Understanding Canada's tectonic history reveals how the country's diverse geology — from Shield to Rockies — came to be. Building Laurentia The core of North America, called Laurentia , began forming over 4 billion years ago. It grew through a process called accretion — smaller crustal blocks microcontinents, volcanic arcs, and ocean floor were welded onto the edges of the growing craton during successive mountain-building events called orogenies . Key Orogenies That Built Canada Trans-Hudson Orogen 1.9–1.8 Ga One of the most important events in Canadian geology. The Trans-Hudson Orogen was a massive continental collision that welded the Superior and Churchill provinces together. It stretches from: - Hudson Bay through Manitoba and Saskatchewan - Into the northern United States This collision was comparable in scale to the modern Himalayan collision between India and Asia. Grenville Orogeny 1.3–1.0 Ga The Grenville Orogeny built a mountain range along the southeastern margin of Laurentia that may have rivalled the Himalayas. Today, the deeply eroded roots of these mountains form: - The Grenville Province of Ontario and Quebec - Parts of the Adirondack Mountains in New York This orogeny occurred during the assembly of the supercontinent Rodinia . Cordilleran Orogeny 200–50 Ma The western margin of Canada was built much more recently through the accretion of exotic terranes — blocks of crust that travelled across the Pacific Ocean and were plastered onto North America. British Columbia is a patchwork of over 20 distinct terranes , including: - Wrangellia volcanic arc rocks - Stikinia island arc complex Supercontinents and Canada Canada has been part of several supercontinents throughout Earth history: | Supercontinent | Age Ga | Canada's Role | |---------------|----------|---------------| | Kenorland | 2.7 | Early Superior craton | | Nuna/Columbia | 1.8 | Trans-Hudson collision | | Rodinia | 1.1 | Grenville Orogeny | | Pangaea | 0.3 | Eastern margin | Active Tectonics Today While most of Canada is tectonically stable, the west coast sits on an active plate boundary: - The Juan de Fuca Plate is subducting beneath the North American Plate off British Columbia - This creates the Cascadia Su