150 EXPLORATION OF THE OAStONS O V F THE COLORADO. 
outlines of the topography are changed, and present angular surfaces, and 
give rise to another type of topographic features, which I have denominated 
Alcove Lands. 
The agencies and conditions under which all of these features have 
been formed deserve mention, and in this and following chapters I shall 
briefly discuss this subject, in a manner as free from technical terms as will 
be consistent with accurate description. 
The discussion will by no means be exhaustive, and I hope hereafter to 
treat this subject in a more thorough manner. In view of these facts, I 
shall not attempt any logical classification of the elements of the topography, 
nor of the agencies and conditions under which they were produced; but, 
commencing at the north, at the initial point of the exploration, I shall take 
them up in geographic order, as we proceed down the river. 
BAD-LANDS AND ALCOVE LANDS NORTH OF THE UINTA MOUNTAINS. 
The area north of the Uinta Mountains embraced in the survey is but 
small. Through the middle of it runs Green Biver, in a deep, narrow val 
ley, the sides or walls of which sometimes approach so near to each other, 
and are so precipitous, as to form a canon. 
The general surface of the country, on the north of this district, is 
about a thousand feet above the river, with peaks, here and there, rising a 
few hundred feet higher; but south, toward the Uinta Mountains, this gen 
eral surface, within a few miles of the river, gradually descends, and at the 
foot of the mountains we find a valley on either side, with a direction trans 
verse to that of the course of Green River, and parallel to the mountain 
range. 
To the north, the water-ways are all deeply eroded; the permanent 
streams have flood-plains of greater or lesser extent, but the channels of the 
wet weather streams, i. e., those which are dry during the greater part of 
the year, are narrow, and much broken by abrupt falls. 
The rocks are the sediments of a dead lake, and are quite variable in 
lithologic characteristics. We find thinly laminated shales, hard limestones, 
breaking with an angular fracture, crumbling bad-land rocks, and homo 
geneous, heavily bedded sandstones. 
