Green River from the U. P. Railway to White River, 
showing gorges through the Uinta Mountains. 
plains with mule teams to Denver, worked along the east slope 
of the Front Range, climbed Pike’s Peak, and went westerly 
as far as South Park. Without realising it, apparently, Powell 
was all these years steadily approaching the great exploit of 
his life, as if led on and prepared by some unseen power. 
Now tk. ^jec^ of exploring the mysterious gorges of which 
378 The Colorado River 
He organised and outfitted at Plattsmouth, Nebraska. All 
his assistants were volunteers except the cook. A. H. 
Thompson, afterwards so closely associated with him in the 
detailed exploration of the Colorado and in subsequent survey 
work, was the entomologist of the party. They crossed the 
