Virtual Museum of Canada

Miguasha : From water to land (The Miguasha National Park)

Tectonic context

Our planet resembles a giant peach. If we could slice through such an enormous fruit, we would see that the peel is like the outer layer of rock on which we live, what geologists call the crust. The Earth’s crust is very thin, extending to depths of 30 to 65 km under the continents, and only 5 to 15 km under the oceans. Beneath the crust (or peel!) lies the Earth’s mantle, which is analogous to the juicy flesh of the peach. The mantle is made of hot rock that can flow slowly, just as you can deform peach flesh as you squeeze it in your fingers. Finally, hidden deep beneath the mantle at a depth of 2,885 km is the outer edge of the Earth’s iron-nickel core – the peach pit if you will! But the similarities end there. The inner core may be solid, but the outer part is hot metallic liquid – the only liquid layer in the planet.

Not all mantle rock can flow easily. The uppermost mantle, along with the thin crust, defines a fairly rigid layer known as the lithosphere. The lithosphere ranges from 10 to 250 km thick and is broken into fragments, called plates, which move around the Earth like pieces of a giant jigsaw puzzle.

Below the lithosphere, enormous heat creates convection cells in the deeper mantle. The stiff lithospheric plates are carried along by these currents of hot flowing rock, much like a conveyor belt. The movement is slow – not much faster than your fingernails grow – but over geologic time, the effect is very dramatic. As the plates move, they carry with them the parts that poke above the water – the continents and islands – and in so doing, constantly reshape the geography of our planet!

This activity, known as plate tectonics, has not been steady over time. Some periods were calmer; others, like the Devonian, much more intense. Where plates moved apart, oceans formed, and where they pushed against each other, continents collided and the towering majestic peaks of new mountain chains emerged from the disappearing Devonian seas...

4,57 billions years of evolution of our planet

Animation  Open this page with video (4.1mo)

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The screen is divided into five sections, presenting the following items:

  • The main screen presents the drifting continents. The film begins 800 million years ago and ends today.
  • Screen 2 presents corresponding dates.
  • Screen 3 presents species present during the corresponding periods.
  • Screen 4 presents the average temperature during corresponding eras
  • Screen 5 presents corresponding periods according to the International Commission on Stratigraphy chart.
Year Species
740 m. years Algae and cyanobacteria
670 m. years Algae and cyanobacteria
610 m. years Algae and cyanobacteria
560 m. years Enigmatic soft-bodied animals
510 m. years Huge diversity of marine animals, several with hard body parts
460 m. years Strange fish swim the seas
410 m. years Flora and small invertebrates appear along the shores
350 m. years Tetrapods along the shores and the first great forests
310 m. years Small reptiles on earth and giant dragonflies in the air
260 m. years Huge reefs in the seas and more and more reptiles on earth
210 m. years Dinosaurs appear, as well as small mammals
160 m. years First feathered birds
130 m. years Bees and butterflies gather pollen from flowers
65 m. years Demise of the dinosaurs and great diversity of mammals
2 m. years Origins of man
15 000 years Modern man is on all continents
Year Temperature
740 m. years Very cold
670 m. years Very cold
610 m. years Very cold
560 m. years 19_C (warm)
510 m. years 20_C (warm)
460 m. years 23_C (warm)
410 m. years 21_C (warm)
350 m. years 16_C (cold)
310 m. years 10_C (cold)
260 m. years 16_C (warm)
210 m. years 19_C (warm)
160 m. years 20_C (warm)
130 m. years 20_C (warm)
65 m. years 17_C (warm)
2 m. years 15_C (cold)
15 000 years 16_C (cold)
Year Periods
740 m. years Proterozoic
670 m. years Proterozoic
610 m. years Proterozoic
560 m. years 542 Cambrian
510 m. years 542 Cambrian
460 m. years 488 Ordovician, 444 Silurian
410 m. years 416 Devonian
350 m. years 359 Mississippian
310 m. years 318 Pennsylvanian
260 m. years 299 Permian, 251 Triassic
210 m. years 200 Jurassic
160 m. years 146 Cretaceous
130 m. years 66 Paleogene
65 m. years 23 Neogene
2 m. years 1.8 Quaternary
15 000 years Quaternary

Moreover, the main screen indicates the location of Miguasha during all these years.