On the lower stretches, from Mohave down, the thermometer in summer stands around 112 degrees F.a great deal of the time, and reaches 118 degrees F.Yet Dr.Coues said he felt it no more than he did the summer heat of New York or Washington.* In winter the temperature at the bottom of the Grand Canyon is very mild, and flowers bloom most of the time.

One November I descended from the snow-covered top of the Kaibab to the Grand Canyon at the mouth of the Kanab, where I was able to bathe in the open air with entire comfort.
* I was at the Needles one summer for a brief time, and the air seemed very oppressive to me.
There are six chief topographical features, canyons, cliffs, valleys, mesa plateaus, high plateaus, mountains.

There are two grand divisions: the lowland or desert, below the Virgen, and the plateau, but the topography of the immediate river course separates itself into four parts, the Green River Valley, the canyon, the valley-canyon, and the alluvial.

The canyon part is the longest, occupying about two-thirds of the whole, or about 1200 miles.

It is cut mainly through the plateaus.
The last of these southward is the Colorado, a vast upheaval reaching from the lower end of the Grand Canyon south-east to about where the 34th parallel crosses the western line of New Mexico.