BITS OF HISTORY: CANADA / A GEOLOGIC GEM IN THE MAKING

Canada's early history, like all nations, is written in her rock. The ground we walk upon today on Turtle Island includes some of the oldest rocks on the planet. 

While you and I were not there to witness it, our planet formed a little over 4.5 billion years ago when a massive collection of dust and gas, the leavings of our newly formed Sun, swirled and spun, gathering into a molten liquid sphere.    

Half a billion years later, our planet began to cool, the molten crust hardening into the first of our tectonic plates. 

These giant puzzle pieces moved together and separated over vast expanses of time to form, pull apart and reform into a series of supercontinents divided by ancient oceans. 

As you explore Canada, you can see evidence of our planet's early history. Canadian geology spans four billion years of Earth history. Four. Billion. Years. Yes, that is quite a bit to process for our young minds. The oldest rocks are preserved in the stable Archean crustal blocks of which the largest include the Superior, Slave, Hearne and North Atlantic cratons. These blocks are also the repository for much of Canada’s gold, copper, iron, zinc and diamonds. 

The Archean cratons were stitched together by Paleoproterozoic mountain belts that resulted in supercontinent Nuna and host important deposits of nickel, copper and platinum group elements. The Mesoproterozoic is dominated by the Grenville orogen another old mountain belt that extends from central Ontario to Labrador. Sedimentary basins of these ages are prominently represented on the opposite (northwest) margin of the Canadian Shield in the Northwest Territories.

The modern geometry of Canada has its origins in the breakup of the supercontinent Rodinia. Neoproterozoic rifting led to new ocean basins and to trailing continental margins now prominently represented in the Appalachians, western Cordillera and Arctic Islands. 

Plate tectonics in the lower Paleozoic introduced oceanic crust to the rock record of Newfoundland and southern Quebec and accretion of exotic crustal fragments in Atlantic Canada and the High Arctic. 

Similarly, warm ocean conditions in Cambrian to Devonian time produced widespread carbonate platforms over the St. Lawrence Lowlands, the Western Interior, Mackenzie Corridor, Hudson Bay and the southern Arctic.

Events of the Mesozoic are prominently represented by the accretion of continental fragments to the western margin of North America — the landmass referred to as Turtle Island by many First Nation, . This remained a tectonically active region into Eocene time and during this interval produced important deposits of copper, lead, zinc, molybdenum, gold, silver, tungsten and other commodities. 

The depositional record of these events is partly recorded in the Western Canada Sedimentary Basin which is a prolific producer of oil, gas and coal. Hydrocarbons are also an important part of the sediment accumulation story since the Jurassic off the East Coast. Likewise, the tectonically active Cretaceous to Eocene record in the Arctic Islands relates to the origin of the Arctic Ocean and the independent plate motions of Greenland.

About 80 million years ago, North America separated from Europe, Australia began to rift away from Antarctica, and India broke away from Madagascar. 

Our northern and southern edges abut the United States. Interestingly, at their nearest points, Alaska and Russia are separated by only 4 kilometres (2.5 miles).