Ancient eras

Ancient eras

If you look beneath our feet (in the right places), you discover evidence of the past eras of the Earth. They are staggeringly old.


For a real world example, let’s look at the Grand Canyon.

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It goes all the way back to the paleozoic.

  • The Vishnu Basement Rocks deposited during the Precambrian-Late Paleoproterozoic Era
  • The Grand Canyon Supergroup deposited during the Precambrian-Mesoproterozoic to Neoproterozoic Era
  • The Tapeats Sandstone deposited during the Early Cambrian Period
  • The Bright Angel Formation deposited during the early to middle Cambrian period.
  • The Muav Limestone deposited during the Middle Cambrian period
  • The Temple Butte Formation deposited during the Paleozoic Era to the Middle to Late Devonian Period
  • The Redwall Limestone deposited during the Paleozoic Era – Late Early to Middle Mississippian Period
  • The Surprise Canyon Formation deposited during the Paleozoic Era – Late Mississippian Period
  • The Supai Group deposited during during the Paleozoic Era – Early Pennsylvanian Period
  • The Hermit Formation deposited during the Paleozoic Era – Early Permian Period
  • The Coconino Sandstone deposited during the Paleozoic Era – Early Permian Period
  • The Toroweap Formation deposited during the Paleozoic Era – Late Early Permian Period
  • The Kaibab Formation deposited during the Paleozoic Era – Early Middle Permian Period

When did all this happen?

  • The Earth was formed approximately 5 billion years ago.
  • The roots of the ancient mountain range that now lies at the bottom of the Grand Canyon were formed about 1.7 billion years ago.
  • There is then an unconformity of about 450 million year in which the rocks are missing.
  • At 1.25 billion years ago the first sedimentary layer, the Bass Formation, was laid down. Ancient coastal dwelling colonies of algae known as Stromatolites are preserved within this layer and indicate that the area was coastal at that time.
  • At 1.2 billion years ago the sea retreated leaving mud flats behind which eventually became the Hakatai Shale.
  • At 1.19 billion years a similar layer was deposited which is known as the Dox Formation. This was again formed of mudstones and shales and contains ripple marks as well as other features that indicate that it was close to the coast.
  • Between 1.25 and 1.1 billion years ago there was also some volcanic activity with the region of the Grand Canyon and this is when the Cardenas Basalts were formed.
  • Between 1 billion and 825 million years ago additional coastal and shallow sea formations, which are now classified as the Chuar group, were deposited.
  • There is then another unconformity of about 250 million years in which new rock layers were probably laid down but were completely eroded away.
  • The Tapeats Sandstone was then deposited around 550 million years ago along long vanished coastline. There are places in the Canyon in which in which off shore islands have been found imbedded within this layer.
  • The Bright Angel Shale was deposited around 540 million years ago and indicates that the ocean was again advancing.
  • The Muav Limestone was deposited around 530 million years ago at the bottom of a shallow sea.
  • The thick layer of Redwall Limestone which began to deposited around 330 million years ago indicates that the land was submerged for a great deal of time.
  • The Supai Group which rests atop the Redwall is dated at 300 million years ago and indicates that it was formed in an above water and coastal environment.
  • The Hermit Shale which was deposited around 280 million years ago contains many plant fossils which indicate that it was also above water.
  • The Coconino Sandstone represents the remains of a vast sea of sand dunes which was blown down from the north around 270 million years ago.
  • The layers found within Toroweap Formation contains both sandstone and limestone, indicating that it was sometimes coastal and sometimes submerged. These layers date to around 260 million years.
  • The top layer of the Grand Canyon, the Kaibab Limestone, contains many marine fossils which indicate that it originated at the bottom of the sea. This layer is around 250 million years old.
  • Rock layers younger than 250 million years have been eroded away and no longer exist in the immediate vicinity of the Grand Canyon.
  • The Rocky Mountains begin to form 60-70 million years ago and at some point later the Colorado River is born.
  • At this point there are at least two popular theories which describe what happens next:
    • Around 20 million years ago the Colorado River begins to carve into the Grand Canyon at its eastern end, Marble Canyon, and probably exiting via Kanab Canyon.
    • At 17 million years ago the Colorado Plateau begins to uplift and causes the river to cut deeper.
    • Around 5 million years ago the uplift ceases and another river working its way northward along the San Andreas fault and eastward along the western Colorado Plateau captures the Colorado River.
  • OR
    • Around 35 million years ago the Kaibab Plateau begins to uplift and diverts the ancestral Colorado, which was already established on a course very similar to that of today, to the southeast. The cut-off western portion, now named the Hualapai Drainage System, contines to drain the western region.
    • About 12 million years ago the Colorado's path to the sea is blocked and a huge lake, Lake Bidahochi, is formed.
    • Eventually the Hualapai cuts back through the southern portion of the plateau and recaptures the Colorado. Lake Bidahochi is drained and becomes the Little Colorado River.


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