CONTENTS. 
Page. 
Introduction 9 
Purpose of the investigation 9 
Extent and character of the investigation 9 
Summary of previous knowledge 10 
General geography 11 
Relation to surrounding regions 11 
Topography 12 
General character 12 
Mountains 13 
Valleys and plains 14 
Descriptive geology 14 
Rock formations 14 
Pre-Cambrian 14 
Cambrian 15 
Carboniferous 15 
Tertiary 16 
Eruptive rocks 16 
Greggs breccia 17 
Quaternary 17 
Temple Bar conglomerate 17 
( 'hemehuevis gravel 18 
Basalt flows .' 18 
( reographic and geologic details of highlands 18 
Grand Wash' Cliffs 18 
Location 18 
Topographic features 19 
Rock masses 19 
Cottonwood and Aquarius cliffs 19 
Location 19 
Topographic features 20 
Rock masses 20 
5fampai < Iliffs 20 
Location 20 
Topographic features 20 
Rock masses 21 
Truxton Plateau 21 
Location 21 
Topographic features 2] 
Rock masses 21 
A quari us Mountains 22 
Location , 22 
Topographic features 22 
Rock masses 22 
3 
