GEOLOGY

A Quick Perspective:
Time, Rock and
The Lake Powell Landscape

By Gary Ladd

The Grand Canyon and Glen Canyon landscapes look ancient and one might be tempted to believe they are truly primeval. They are, indeed, very old. But so vast an amount of time has elapsed since Earthís creation that these canyons might be considered upstarts. Take a moment to examine a list of events that lend a sense of perspective.

• The Universe forms:

• About 15 billion years ago.

• The Earth forms:

• 4.6 billion years.

• The Moon forms:

• 4.5 billion years.

• Oxygen begins to accumulate in Earthís air:

• 2.2 billion years ago.

• Age of the oldest Grand Canyon rock:

• 1.8 billion years.

• Plants begin to colonize dry land:

• About 450 million years ago.

• Animals first venture onto dry land:

• About 425 million years ago.

• Age of the youngest Grand Canyon rocks:

• 260 million years.

• Occurrence of "The Great Dying" when most of Earthís plants and animals perished. (The cause is unknown):

• 245 million years ago.

• Age of Glen Canyon area rock layers:

• 280 to 70 million years.

• Age of Navajo Sandstone:

• Around 190 million years.

• North America begins to uncouple and drift westward and away from Europe:

• About 150 million years ago.

• Age of the Rocky Mountains:

• About 65 million years.

• A giant meteor crashes into Earth near the Yucatan Peninsula, apparently causing the extinction of many plant and animal species including the dinosaurs:

• 65 million years ago.

• AGE OF GLEN AND GRAND CANYONS:

• ABOUT 5 MILLION YEARS.

• The first true humans appear in Africa:

• About 3 million years ago.

• Creation of Meteor Crater:

• About 40,000 years ago.

• America via the Bering Land Bridge:

• 11,500 years ago.

• Creation of Crater Lake, Oregon:

• 6,800 years ago.

• Colonization of Hawaii by Humans:

• About 2,000 years ago

• Invention of baseball:

• Almost 200 years ago.

• Age of Lake Powell:

• 33 years.

Today's scenery is newfangled. Its rocks may date to hundreds of millions of years in age but the topography is young. The mesas and buttes that have been cleaved from the rock layers are works-in-progress. Individually they began to take shape hundreds of thousands of years ago. Their familiar outlines began to emerge, perhaps, tens of thousands of years ago. And in most cases their details have been shaped in only the most recent hundreds to thousands of years.

Enjoy Lake Powell. But remember to be gentle with the landscape that surrounds its waters. The slickrock terraces, cliffs and slot canyons are newborn, unique and fragile.