DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, DIRECTOK BULLETIN 467 GEOLOGY AND MINERAL RESOURCES OF PARTS OF THE ALASKA PENINSULA BY WALLACE W. ATWOOD WASHINGTON GOVERNMENT PRINTING OFFICE 1911 CONTENTS. Page. Preface, by Alfred H. Brooks ............................................. 7 Introduction............................................................. 9 Location and extent of area considered................................. 9 Previous explorations and surveys..................................... 9 Acknowledgments.........................................;.......... 12 Character of the country.................................................. 13 Geography........................................................... 13 Mountains....................................................... 1.3 Lowlands........................................ ................ 14 Coasts ........-........-....-.---..-----------..---....---.----.- 14 Drainage..................................-.------ -- -- --- ---- 15 Climate.............................................................. 15 Vegetation............................................................ 17 Settlement........................................................... 18 Commercial development.............................................. 19 Transportation .....................................................*.. 22 Geology ................................................................. 23 General features...................................................... 23 Age and succession of the rocks ................ .................... 23 Distribution of formations. ........................................ 26 Structure ........................................................ 27 Stratigraphy ..................................................... 29 Character and distribution of the rocks................................. 30 Argillite of unknown age.......................................... 30 Triassic system................................................... 30 Jurassic system................. .................................. 31 Lower Jurassic rocks......................................... 31 Granites and syenites, probably of Lower or Middle Jurassic age. 31 Middle Jurassic rocks ("Enochkin formation")................ 32 Upper Jurassic rocks.......................................... 33 Naknek formation........................................ 33 Cretaceous system................................................ 38 Lower Cretaceous rocks....................................... 38 Staniukovich shale....................................... 38 Herendeen limestone...................................... 39 Fauna..................................................... 39 Stratigraphic relations.................................... 40 Upper Cretaceous rocks. ........................................ 41 Chignik formation.................. _ ..............!..... 41 Tertiary system ................................................... 48 Basaltic flows, breccias, agglomerates, and tuffs of early Eocene age........................................................ 48 Eocene series .................................................. 49 Kenai formation.......................................... 49 Oligocene series (?)........................................... 59 Late Eocene or early Miocene andesites, tuffs, breccias, and glass. 59 4 . CONTENTS. Geology Continued ' Page. Character and distribution of the rocks Continued. Tertiary system Continued. Late Eocene or later igneous rocks............................. 63 Augite porphyry flow breccia.............................. 63 Dacites.................................................. 63 Diorite-porphyrite........................................ 65 Miocene series ... ........................................'... 66 Unga formation .......................................... 66 Post-Miocene basaltic flows and tuffs.......................... 69 Pliocene series (?).-...-...................................... 71 Summary of the igneous rocks................................. 71 Quaternary system ................................................ 73 Pleistocene deposits ....................... 1................... 73 Eecent deposits .............................................. 75 Geologic history........................................ .................. 76 Early Mesozoic time................................................... 77 Late Mesozoic time................................_.................. 78 Tertiary time ..:..................................................... 79 Quaternary time ...................................................... 81 Geomorphology.......................................................... 81 Means of interpretation............................................... 81 Eocene sedimentation and the growth of the Aleutian Range............ 82 Miocene erosion and possible planation ................................ 82 Deformation at the close of the Miocene............................... 83 Pliocene erosion................................ '.. ...............I..... -83 Glaciation .............................................I.........._.. 84 General effects................................................... 84 Glaciation of Unga Island..................................... .... 85 Glaciation of Popof Island......................................... 87 Glaciation of the Balboa-Herendeen Bay district................... 87 Glaciation of the Chignik Bay region .............................. 90 Retreat of the ice.................... 1............................ 91 Post-Pleistocene erosion .............................................. 92 Modern shore lines.-.................................;'................ 92 Recent changes in level............................................... 94 Summary of late geologic history....................................... 95 Mineral resources ........................................................ 95 Distribution of known mineral resources............................... 95 Coal................................................................. 96 Herendeen Bay coal field......................................... 96 Geography .................................................. 96 Areal extent.................................................. 97 Geology..........;............................................ 97 Stratigraphy............................................. 97 Structure................................................ 98 The coal measures............................................ 100 Character of the coal......: ........:.......................... 103 Physical properties.......................... 1............ 103 Combustion.............................................. 104 Chemical and calorimetric properties ...................... 104 Prospective mining conditions................................. 106 Position of the coal measures.. ........................... 106 Dip of the coal measures.................................. 106 Extent of the coal measures............................... 107 Shipment.................................................... 107 CONTENTS. 5 Mineral resources Continued. Pa&e. Coal Continued. Chignik Bay coalfield.........----.-.---....--.----....--......--. 108 Geography................................................... 108 Areal extent ................................................. 109 Geology .................... T ................................. 109 Stratigraphy............................................. 109 Structure ................................................ 109 The coal measures............................................ 110 Character of the coal .......................................... 114 Physical properties....................................... 114 _ Combustion.............................................. 115 Chemical and calorimetric properties ...................... 115 Prospective mining conditions................................. 115 Position of the coal measures.............................. 115 Dip and extent of the coal................................. 116 Shipment................................................ 116 Cold Harbor coal field............................................ 117 Geography .....................................i............ 117 Development work........................................... 117 Areal extent................................................. 118 Geology...................................................... 118 Character of the coal ................................. ........ 119 Prospective mining conditions................................. 4 120 Petroleum ........................................................... 120 Cold Bay oil field................................................. 120 Geography ...'............................................... 120 Geology ..................................................... 121 Stratigraphy............................................. 121 Structure................................................ 122 Indications of petroleum....................................... 122 Seepages..............................................;.. 122 Developments..............................'.'.............. 122 Character of the oil....................................... 123 Other possible petroleum fields.................................... 124 Gold..........................!..................................... 125 Popof Island...................................................... 125