A state-of-the-art mine in Goderich, Ontario, is the entrance to what was once a vast, tropical sea that lay in the middle of North America, over four hundred million years ago during the Silurian period. As the continent shifted away from the equator the sea disappeared but the salty deposits on its bottom remained.

More than five hundred metres underground, towering salt pillars gleam inside the mine’s walls. Like a coded message, the white layers record periods of extreme heat and dark, cooler, wet weather. It’s a fascinating record of seasonal patterns that spans several hundred years. The same deposit is found deep below the city of Detroit, Michigan.

Today, that ancient salt is hauled to the surface and shipped all around the Great Lakes region.


  • The Sifto salt mine in Goderich, Ontario is the largest in the world. It extends five kilometres under Lake Huron.
  • A team that was originally drilling for oil in the area first struck rock salt in 1866. The rock salt, discovered more than 300 metres feet beneath Goderich Harbour, was the first recorded discovery of a salt bed in North America.

  • The Great Lakes
    Discover the roots of a long vanished mountain range, explore the remains of an inland tropical sea and trace the story of a dramatic flood
  • The Rockies
    An ever-changing landmass, geologists are learning how the Rockies were formed and discovering what they will become.
  • The Canadian Shield
    The largest - and one of the oldest - expanses of ancient rock on the planet has riches of gold and diamonds under it's crust.
  • The Appalachians
    These fabled mountains contain a geologic puzzle, a rich legacy, and the scarcely known threat of earthquakes.
  • The Atlantic Coast
    The dramatic story of volcanic outpourings, massive rifting of continents and the bursting forth of a new ocean - the Atlantic.

A five-part series that chronicles the incredible—and surprising—history of Canada's landscape in HD.

Canada Rocks Read an excerpt from Canada Rocks, a new book by the scientific advisor to Geologic Journey, Nick Eyles.

Watch video interviews with some of the scientists featured in Geologic Journey (produced in conjunction with National Sciences and Engineering Research Council of Canada).

Order the Geologic Journey DVD for classroom use and download Teacher Resource Materials.
The Nature of Things with David Suzuki