UNITED STATES DEPARTMENT OF THE INTERIOR Harold L. Ickes, Secretary GEOLOGICAL SURVEY W. C. Mendenhall, Director Bulletin 865 GEOLOGY OF THE MONUMENT VALLEY-NAVAJO MOUNTAIN REGION, SAN JUAN COUNTY UTAH BY ARTHUR A. BAKER UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1936 For sale by the Superintendent of Documents, Washington, D. C. ------ Price 60 cent' CONTENTS WQU, Pag. Abstract--------------------------------------------------------- 1 Introduction. ___.__--______-_-___-_-______ -__-___-.-_-____ 3 Location and extent of area---'---- ---------.-------------.--. 3 Present investigation._____ _____-_-_______-___-_-_ _________ 4 Acknowledgements.______._____-_-_---___-_-___-_--__---______ 5 Geography----------------------------- -------- ________ 6 Surface features...__--_-_.------- __________________ 6 General features... -. 6 Canyons of the San Juan and Colorado Rivers ______ 7 Upland surface of the region _-_. 8 Drainage and water supply _' _-._ ... 10 Climate and vegetation.._.---_--_______-_-__-_._______--____._ 12 Population ________-_-__-------------------------------------- 13 Accessibility and routes of travel __ _______ ______ 14 Fuel... r - -2 16 Land surveys --------- ---- ---- - - 16 Previous publications...__-_--_.---_-----_____-__-_,_---_-_--._.___. 16 Stratigraphy ._______--_--_-_---_-_---------__-------_-_-___-_ 18 General features--------------------.------------------.--.--- 18 Carboniferous system _. ____-__. ____ ___________ 18 Pennsylvanian series....-___-.._____-___-___-______.___._-. 18 Hermosa formation.--_--_..______-.____-_____________. 18 Permian series_-------------------_---_---_------_----_-__ 24 Rico formation....-__-_._-______.____.-_________-____ 24 Cutler formation.._-_-_-___-_________________---______ 28 Halgaito tongue ________________________________ 29 Cedar Mesa sandstone member.____________________ 31 Organ Rock tongue....____________________________ 33 De Chelly sandstone member__________________ 35 Hoskinnini tongue____________________________ 38 Triassic system._ .. 40 Lower Triassic se"ries___---_-__-_-___-____ ______________ 40 Moenkopi formation ____________ _______________ 40 Upper (?) Triassic series--__-___-_________.________________ 44 Shinarump conglomerate...--._________________________ 44 Upper Triassic series____-______________________.________ 47 Chinle formation__________________________________ 47 Jurassic (?) system......_-_---_-_--__-_ ._ 48 Glen Canyon group____--__--__-_________-_-____________ . 48 Wingate 'sandstone----_-__-_.____-_-__-__-_-_________. 48 Kayenta formation.___________________________________ 50 Navajo sandstone..______-_______-_-_-________-______- 53 Jurassic system______-_---_-_-_--________-_-___________-______ 55 Upper Jurassic series._____________________________________ 55 San Rafael group___-_____--___._______._.____,.._____ 55 Carmel formation_________________________________ 55 Entrada sandstone_________-_____________.________ 57 Morrison formation____________________.____-._._.___- 58 ni IV CONTENTS Stratigraphy Continued. Page Cretaceous system. ___________________________________________ 59 Upper Cretaceous series._________________________________ 59 Dakota (?) sandstone________________________________ 59 Tropic shale and Straight Cliffs sandstone______________ 60 Tertiary (?) system.__________________________________________ 61 Quaternary system.-_____________-____-___--_-__--______--____ 62 Igneous rocks___________________________________________________ 62 Structure _____________-_-__-__---_-___-__--__--_---_-__-___--_-__ 63 General features.___________-__-______-___--_--_________-__-__ 63 Methods of representing structure____---________________________ 64 Details of folds-_____-_____-------_---_-___-_-----_----_----.._ 65 Halgaito anticline____--_--__-_--___-___-__--_---_-_----_-_ 65 Oljeto syncline..____---_-----_____-__--__--_---_-----__._ 66 Organ Rock anticline.___-___-______-______--_-___----___-_ 67 Nokai syncline---_-_-------_-_---_------------_---___---__ 68 Balanced Rock anticline-------__--_-_-_--_------_-__--_-__ 69 Rapid syncline__________--_--__--__-__-_----------__-____ 70 Beaver anticline_-________-__--_--__-__---_--_--_---_---_- 70 Navajo Mountain dome_-__-_-__--_---_---_-__---_____-_-_ 71 Minorfolds___-__-___------_----_---___--__-__-______ 72 . Faults.______________-___----_-_----_---___--_-___________ 73 Periods of deformation_-___-____-------_____---_-_._-___-______ 74 Geomorphology -_-_________--_---_----_-_-_---__-__-___-_________.. 76 Early geomorphic history______________________________________ 76 Erosion surfaces and terraces_-__-_____________________-________ 76 San Juan and Colorado Rivers-_-___--____--___-________________ 80 Tributary streams-_-_-_-_---__--__-__-_-_-____________________ 82 General surface features.___-_---__--_--_______________________ 84 Mineral resources _________________________________________________ 86 Oil--.-.----. ---_--- -------_-__--__-___--.___-__ 87 Oil seeps--___--_-__-_-_-__--______-___-_-_____-______ 87 History of drilling_______________________________________ 87 Character of the oil-____-__--_____-_____---_______________ 91 Possible results of further drilling.__________________________ 92 Stratigraphic evidence._____-__-___-__ ,____-____________ 92 Structural relations__________________________________ 95 Conclusions ______________________________________________ 97 Gold._______________________________________________________ 98 Copper---.--..-..--..-.---.---.--.--.---.-.i.-.-.-.-..-..... 99 Well records________________________________________________ 99 Index________________________________________________________ 105 ILLUSTKATIONS Page PLATE 1. Geologic map of the Monument Valley-Navajo Moun­ tain region, Utah_____________.____________________ In pocket. 2. Reconnaissance topographic map of the Monument Val­ ley-Navajo Mountain region, Utah__________________ In pocket. 3. Block-diagram showing the surface features of the Monument Valley-Navajo Mountain region-______-_______^_Vtv^- j .£:AO 4. A, Panoramic view of the east-central part of the Monument '^ ''U, Valley-Navajo Mountain region from the northeast corner of Hoskinnini Mesa; B, Panoramic view of lower Copper Canyon from the east rim______-__-____-_______________ 10 5. Rocks exposed in Monument Valley-Navajo Mountain region.. 18 6. Sections showing lateral variations of some of the formations exposed in the Monument Valley-Navajo Mountain region. _ 18 7. A, Canyon of the San Juan River looking south from a point near the mouth of Johns Canyon; B, Canyon of the San Juan River looking north from a point near the west quarter cor­ ner of sec. 30, T. 41 S., R. 18 E_________________________ 18 8. A, Organ Rock, in sec. 21, T. 42 S., R. 14 E.; B, Jacobs Monu­ ment, in sec. 27, T. 42 S., R. 13 E.; C, Narrow canyon cut in Cedar Mesa sandstone member of the Cutler formation by the San Juan River below the mouth of Oljeto Wash.. 34 9. A, View of east side of Wide Butte in sec. 14, T. 43 S., R. 16 E.; B, Train Rock, one of the monuments of Monument Valley, in sec. 33, T. 42 S., R. 15 E., and sec. 4, T. 43 S., R. 15 E.; C, View north toward the San Juan River from top of cliff in sec. 12, T. 42 S., R. 13 E-_--._-------__-....__....__ 34 10. A, Cross-bedding in the De Chelly sandstone member of the Cutler formation on the east side of the Rock Door, in sec. 35, T. 43 S., R. 15 E.; B, East side of the canyon of Nokai Creek, in sec. 11,T. 43 S., R. 12 E.-_-__-.__.___..__.--_ 34 11. A, Massive Shinarump conglomerate grading laterally into banded variegated shale of the Chinle formation in sec. 22, T. 41 S., R. 13 E., southeast of Monitor Butte; B, West side of Redbud Pass, a narrow cleft in the Navajo sandstone west of Navajo Mountain_________-_--_--__-______.__._ 34 . 12. A, An outcrop of the Shinarump conglomerate in sec. 29, T. 41 S., R. 13 E., showing the irregular bedding of the formation; B, West wall of Piute Canyon in the southern part of T. 42 S., R. 11 E.; C, Outcrop of the rocks of the Glen Canyon group in the,, canyon of-the San Juan River southeast of the south quarter corner of sec. 4, T. 41 S., R. 11 E_----___________ 50 13. A, East side of Navajo Mountain from the Wetherill Trading Post; B, Joints in the Navajo sandstone on the east side of Redbud Pass.________________________________________ 50 14. A, An outcrop of the Navajo sandstone in a butte on the west side of Surprise Valley; B, Closely spaced rounded domes of Navajo sandstone on the north side of Redbud Canyon about 1 mile from its junction with Bridge Canyon; C, North wall of the canyon of the Colorado River about 9 miles west of the Monument Valley-Navajo Mountain region______________ 58 VI ILLUSTRATIONS Page PLATE 15. A, A remnant of an old erosion surface, possibly of Tertiary age, north of Navajo Mountain; B, Alhambra Rock, a dike of igneous rock that makes a prominent landmark near the canyon of the San Juan River at the east edge of the area._ 58 16. A, Panoramic view of the Balanced Rock anticline looking north from the trail to Piute Mesa near the southeast corner of sec. 28, T. 41 S., R. 12 E.; B, Upstream side of Rainbow Natural Bridge__________________________ 74 17. Generalized block diagram of a part of Bridge Canyon..___ 82 FIGURE 1. Index map of Utah showing the location of the Monument Valley-Navajo Mountain region___ ____________________ 3 2. Diagram showing the geographic subdivisions of the Monument Valley-Navajo Mountain region______________________ 9 3. Restored cross section along the Colorado and San Juan Rivers showing