WSP04016

• File Number: 8220.200.05.J
• Description: Hoover Dam/Lake Mead/Boulder Canyon Project
• Basin: Colorado Mainstem
• Date: 1/1/1950
• Author: USDOI/BOR
• Title: Boulder Canyon Project Final Reports: Part III/ Bulletin 1 - Geological Investigations
• Water Supply Pro - Doc Type: Report/Study

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CONTENTS

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Section

REGIONAL STRUCTURE

25 General characteristics -----_______________________________~_____~____ 32
26 Intermountain faults _____________________________.._______~__________ 33
27 Faults within ranges n____n___n__n_h___________nn_n__hn_hn 33
28 Folds n_n_n______n___n_nn__nn________n..n__n__n_n___n 33
29 Thrusting ________________________._________________________ _________ 33

AGE AND HISTORY OF THE COLORADO RIVER
30 General discussion ---___________________________________________n__ 34

CHAPTER III-GEOLOGIC FEATURES OF BOULDER CANYON

INTRODUCTION
31 Location and description_n_n_____________n___n______nn______n_ 37
32 Topographic features __~~_____~______________________________________ 37

GEOLOGIC FORMATIONS
33 General description nn____n_nn___n__nn__n_____n_n__hn_n_ 39
34 Pre~Cambrian schist nn____n____________n_______n_____________n_ 40
35 Quartz diorite _____________n___________________________________u_ 40
36 Pre-Cambrian granite ____________________________________________n_ 41
37 ])ikes -____________________________________________________________ 41
38 Comparison of granite and quartz dioritenn__n_____..n__nn__n___n_ 41
39 Boulder V7ash group ________________________________________________ 42
40 River.fill __________________________________________________________ 43

STRUCTURAL FEATURES
41 General description ________________________________n___n__________ 43
42 Boulder Wash fauIL_________________________________________________ 44
43 Two-Mile fault _____________________________________________________ 45
44 Other faults _______________________________________________________ 45
45 Boulder Canyon not related to faulting___n____n_________n___nhn___ 45
46 Jointing _ _____ nn _n__ _ ___ _ _ ___ _ _ ___n _____ ______ _n_ _ __nn __ _ __ __ 48
47 Major joints ________________________________________________________ 48
48 Minor joints _______________________________________________________ 48
49 General effect of jointing_____n_n_n_______nn________n_n_________ 48

CHAPTER IV-INVESTIGATIONS IN BOULDER CANYON

INTRODUCTION
50 Reconnaissance of 1920 ___________n__n___________n________________ 49
51 Tentative dam sites ____n________n__________n_____n___n___n____ 50
52 Topography and general geology__n___________n____~n_________n___n 50

SITE A
53 Location and descriptioohn__________n_____n____________n___n____ 50
54 Exploratory drilling ________h________n____________h_______________ 50
55 Geologic section on line A-I n_n__hn_nn___n___'________________n 53
56 Geologic features ___n____n_________________n___hn__n____n_____ 54
57 Summary ____________~ _______________________________~_____________ 54

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