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Explosive Prehistoric Volcanic Eruptions |
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How the Mighty
Grand Canyon Formed
Hot magma, flowing from the depths of the the crust built
magnificent stratovolcanoes. Explosive volcanic eruptions
submerged the region under ash, volcanic debris and lava flows. Deep
underneath the volcanoes were pockets of molten rock (called magma
chambers) that supplied the volcanoes above. As new chambers and
volcanoes formed, older magma chambers cooled to form solid igneous
rock masses called plutons.
The development of what is today known as Lake Mead and Grand Canyon
began as weakened, stretched crust fractured and faulted. Huge
blocks of crust slid down along faults, creating abysmal basins
which filled with sediment eroded from the neighboring uplifted
blocks almost as fast as they subsided. Extensive lakes formed where
water was trapped by the massive newly developed mountain ranges.
The Birth of the
Colorado River
Volcanic activity and faulting in the Lake Mead region continued
until about 2 million years ago when another geologic event was
about to begin that would forever change the Lake Mead landscape.
Approximately five million years ago the
landscape was towered by elongate ridges
that had shed thick fans of sediment into
neighboring valleys. A small stream that
flowed from the Lake Mead region into the
Gulf of California had been steadily
eroding northeastward bit by bit. Finally,
it cut through the cliffs at what is now
the mouth of the Grand Canyon near Pierce
Ferry. This is the birth of the Colorado
River as we know it today!
A Brief History of the Grand Canyon >>
View Grand Canyon Map >> |
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The
Great Chasm - The Grand Canyon |
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