Michael Lowell, age 94, of Warwick, R.I., for his question:
HOW BIG IS THE GRAND CANYON?
On just about everybody's list of the Seven Natural Wonders of the World you'll find the Grand Canyon. And what a wonderful place it is. It's like a showcase where the entire natural history of a changing world can be seen ¬and a location where many types of animals and plants can be found living from mountain top to desert floor.
Although the Grand Canyon of the Colorado River isn't too large, on display is just about every type of terrain you can imagine. Included is the full 250 mile length of the river, and along the way you'll find desert country, cliffs, hills, ridges, valleys, rocks and mountains. Highest points on the north rim are about 9,000 feet above sea level.
Something like 1.2 million acres are included in the Grand Canyon National Park. The river rushes along about 1,800 feet above sea level.
More than 200 different kinds of birds live in the park. In addition, living there are more than 100 other animals, including mountain lions, beavers, bighorn sheep, deer, porcupines, antelopes and snakes. Just to the north, in the Kaibab National Forest, you'll find the Kaibab squirrel. It's the only place in the world where he lives.
The Grand Canyon, scientists tell us, was formed over millions of years. The cutting force of the river has carved out a deep and wide slash on the northwestern Arizona landscape.
The bottom layer of rock on the floor of the canyon is black in color and called Archean. The second layer, called Algonkian, is brilliant red. Next comes the Tapeats sandstone layer which is lavender brown. The fourth is the Devonian layer which is made up of small deposits of lavender rock. The thick Redwall layer comes next, with 800 feet of red sandstone above that called the Supai formation.
But you're still not at the top. Above the Supai formation is the Hermit shale, another layer of red. Next comes the Coconino sandstone layer, 350 feet of pale sand¬colored stone. At the top is a layer of cream and gray Kaibab limestone.
Pueblo Indians once lived in the Grand Canyon area. Today about 200 Havasupai Indians live as farmers in one remote section called Havasu Canyon. And, of course, thousands of tourists visit annually.
Grand Canyon National Park was established in 1919. In 1974, Congress passed a bill that almost doubled the size of the original park. Added was Grand Canyon National Monument and Marble Canyon National Monument as well as sections of Glen Canyon National Recreational Area, Kaibab National Forest and the Lake Mead Recreation Area.