X PREFACE, 
It is expected that the results of these labors will, as soon as practica 
ble, be published by the General Government, in a series of volumes, and 
such publication commences with the present, which, in Part First, gives a 
history of the original exploration through a region practically unknown 
prior to the time it was made. It has not been thought best to give a history 
of all our travels, but only those portions which were original explorations. 
Accompanying the volume will be found a map of the " Green River 
from the Union Pacific Railroad to the mouth of the White River," including 
the eastern portion of the Uinta Mountains, and a " Profile of the Green 
River and Colorado River of the West, from the crossing of the Union 
Pacific Railroad to the mouth of the Colorado, compared with the profile 
of the Ohio and Mississippi Rivers from Pittsburgh to Vicksburgh." It has 
been prepared from barometric data collected at different times during the 
exploration and survey. That portion below the mouth of the Rio Virgen 
has been taken from Lieutenant Ives's u Report upon the Colorado &iver of 
the West." 
The altitude of the mouth of the Rio Virgen is represented on the pro 
file with this volume as somewhat less than it appears on that made by 
Lieutenant Ives. Our own determinations fix it as we represent it. Lieu 
tenant Ives's data for the upper portion of his line are indefinite, but can be 
interpreted to agree with the results which we have obtained ; perhaps 
better than with his own profile. 
As far as possible we have adopted the names of geographic features 
used by the settlers of the adjacent country, but many of the mountains, 
plateaus, valleys, canons, and streams were unknown and unnamed. In 
such cases we have accepted the Indian names, whenever they could be 
determined with accuracy. I intend, finally, to publish a glossary of all 
these new names, giving their significance. 
I am greatly indebted to many gentlemen living in Utah, Wyoming, 
and Colorado Territories for their assistance and co-operation in this enter 
prise. To mention them severally would inordinately swell this preface. 
Professor A. H. Thompson has been my companion and collaborator 
during the greater part of the time, and has had entire charge of the geo- 
