Final answer:
The Grand Canyon is very old by Earth history standards, with a geologic landscape ranging from 1,840 to 270 million years old. The Colorado River established its course through the canyon about six million years ago.
Step-by-step explanation:
The Grand Canyon is very old by Earth history standards. It preserves a geologic landscape ranging from 1,840 to 270 million years old. The Colorado River established its course through the canyon about six million years ago. The canyon itself is immense, averaging 4,000 feet deep for its entire 277 miles.