About 70 million years ago the collision of tectonic plates caused the
Colorado Plateau to rise from sea level to 10,000 feet. Then the
Colorado River began its work of cutting through the rock, a powerful
force chiseling away at limestone, sandstone, shale, schist and gneiss.
Wind, rain and melting snow contributed to the erosion. Rocks split off
and came crashing down. Slowly, the canyon's magical formations took
shape.
As the Colorado River continues to wind its way through the Grand Canyon
like an unfurling ribbon, the process of sculpting also goes on one
inch every 500 years.
Today, some of the exposed canyon walls are a fascinating geology
lesson, their layers a history of the earth through time. The oldest
rocks at the bottom of the canyon (gneiss and schist) go back 2 billion
years. Kaibab Limestone, deposited 260 million years ago, forms most of
the cap rock.
|
