Yet here it is already 3500 feet below the surface at the end of Marble Canyon, which, separated only by the deep canyon of the Little Colorado, is practically a northward continuation of the Grand Canyon itself.

As the river runs, the Grand Canyon is 217 1/2 miles long.

To this may be added the 65 1/2 miles of Marble, giving a continuous chasm of 283 miles, the longest, deepest, and most difficult of passage in every direction of any canyon in the world.

The depth begins with a couple of hundred feet at Lee's Ferry (mouth of the Paria), the head of Marble Canyon, and steadily deepens to some 3500 feet near the Little Colorado, where the sudden uplift of the Kaibab lends about 2000 feet more to the already magnificent gorge.

Along the end of the Kaibab the walls, for a long distance, reach their greatest height, about 6000 feet, but the other side is considerably lower than the north all the way through.