STATE OF OREGON DEPARTMENT OF GEOLOGY AND MINERAL INDUSTRIES .702 Woodlark Building Portland 5, Oregon " Bulletin No. 27 Geology and Coal Resources of the Coos Bay Quadrangle, Oregon by John Eliot Allen and Ewart M. Baldwin State of Oregon-Coos County Coal Survey 1944 STATE GOVERNING BOARD • • • • W. H. STRAYER, CHAIRMAN BAKER . • NIEL R. ALLEN . GRANTS PASS . • S. H. WILLISTON . PORTLAND F. W. LIBBEY DIRECTOR Oregon Department of Geolog y Plate 2 and Mineral Industries Bulletin 27 :::: Air view of coastal section looking east. Lighthouse Point in the foreground, Yokcm Point (Mussell Reef) and Coos Head in the middle dtstance Copyright Brubaker Aerial Surveys. FOREWORD The State Department of Geology and Mineral Industries presents the ensuing report in accordance with the directive of the forty-second regular session of the Oregon legislative assembly, as set forth in chapter 350, page 470, of the 1943 Session Laws. The purpose of the investigation described in the report was to make available information, both geologic and economic, which would encour­ age, promote, and increase commercial production of Coos Bay coal. To this end, exploration by drilling of shallow coal was carried out and a detailed study of the geology was made, supplementing the pioneer work of J. S. Diller of the U. S. Geological Survey and later workers. Deep drilling to test continuity of coal beds was not attempted because the U. S. Bureau of Mines was engaged in that type of exploration. This work by the Bureau is being continued in November 1944. The value of exploration work in the form of drilling and sampling is understandable to everybody. The value of regional geologic study in relation to exploration work is not so generally appreciated. Coal· fields are usually of considerable areal extent and the coal may occur in several beds. Thus to understand characteristics of any local area in the coal field, all possible evidence must be gathered in a study of the regional geology in order to recognize structural relationships; to project strike and dip of beds and faults, and to determine areal extent of coal-bearing horizons. This report represents a large amount of work, both in the field and office. It is believed that results of the study will be of much tangible value not only to Coos County but to the state as a whole. In addition, it is believed that the report is an important contribution to knowledge of the geology of the state. F. W. LIBBEY, Director. · November 4, 1944. iii GEOLOGY AND COAL RESOURCES OF THE COOS BAY QUADRANGLE OREGON Contents Page Foreword _____ ____________ _ ii i Abstract ______ 1 Introduction 3 Purpose and scope of survey _ 3 Acknowled gments ______ _ 3 Princ ipal conclus ions ____________________ 4 Part I: GENERAL GEOLOGY Introduct ion __________ ----------------- 7 Lo cation and access ibility ____ _______________ 7 Reli ef and drainage _____ 7 Cl imate and vegetat ion _ _ ____________ _ 7 Populat ion and in dustry ___ ________________ _ ___ __________ __ _ 7 Strat igraphic ge olo gy _____ _ 8 Prev ious work ______ _ 8 Pre-Tert iary rocks _______ ________ 9 Introduct ion 9 Peridot ite __ 10 Sed iments 10 Basalt _______ . _ ______ ______ 11 Sch is ts . --------------- 11 Tertiary format ions __ ----- --------- ----- ------------------------- 13 Umpqua formation _____ __________ -------------------------------- 13 Volcanic ser ie s (interca lated with Umpqua format ion) 16 Tyee sandstone ___ ----------------- 19 Lo wer Coaledo _______ __ ------------ ------ 21 Middle Coaledo , 23 Upper Coaledo ________ __ ____ 25 Bastendorf shale -----------­ 27 Tunnel Point san dstone 28 Empire formation -------·--· 29 Port Orford formation 31 Qu aternary format ions 31 Coqu llei format ion 31 Elk River bed s 32 Alluvium ____ . 32 Structural ge olo gy ____ 33 General features B3 Fold ngi -------------···- -·---···-·-··­ 33 Cape Ara go ant icline 34 South Slou gh ba si n _ 34 Westport arch ______ _ 34 Emp ir e bas in ----·-------------------···-·--·····---- . 34 Western fork of the We stport arch . ________________ 34 .. Newport bas in ____ _ _______ ______ _______________ _ 34 North Bend bas in ----------------········-·---- ------ ------------ ---··-- 34 Eastern fork of the Westport arch ___ ---·---------- --------··-·-------- 35 . Beaver Slou gh bas in ····---·········--·------------ --------------·· 35 . Catch ingSlou gh-Coaledo arch ______ 25 Sumner bas in _____________ 36 Pulask i arch ___ --------------------····-------- 36 Co quille b ··------------- ···-·-··· __________________ 36 asin Norway anticl in e ············----···· ------------·······- --··-···------------------··········------------------ 37 iv CONTENTS-Continued Page Ha ll Cree k folds ------------------------------ ______________ _ 37 Myrtle Po in t fo lds _ _ __________________ _ 37 Bill Pea kant icl ine __ ------------------- 37 Tyee fo lds ----------------- ------ -------------------- 37 Str ike fa ults ___________ ___ ____________ 37 Isthmus Slough fa ult _ _ _______________ ____ 37 Cape Arago fa ult __________ --------------------- ---·· 38 Blue Mounta in fa ult _ _____________ _____ 38 Sumner fault ____________ _ 38 Ch ina Camp Cree k fa ul t __ ________ __ _____ _________________________ 38 Transverse fa ults -------------------- 38 Beaverton fa ult ______ ____ _ 39 Dav is Slough fa ult 39 Mill Slough fa ult _____ _ 39 Lillan i fa ult ----------­ 39 Threem il e Cree k fa ult _ 39 Minor fa ult in g ------------------ 39 Summary ofage and or gini of st :'Ectu ral feaLres ___ 40 Phys io graphy ------------------------ ________________ ---------------------------------- ------ ------ ----- 42 Topograph ic divisions _ _ _____________ _ 42 Relat ion oftopography to lithology and struct c:re ___ ----------------- -------- ----------------- ------ 42 Effe cts of sea level changes upon topography _ --------------- 43 Fl ood pla ins ----------------------------------------------------------- 44 Geolog ic history ____ ------------------------------ ________________ _ 45 Pre-Tert iary ___ _ 45 Tert ia ry _______ _ 45 Eocene 45 Ol igocene __ 47 Miocene _ 47 Pl iocene _ 48 Qu aternary ______ _______________ _ 48 Ple istocene and Recent 48 Part II: COAL RESOURCES Introduct ion ___________ -------------------- ---------------------- --------------------------------------------------------------- 51 History ofcoal product ion __ 51 Past in v€st igat ions -------------- 51 Present in vest igat ions and summary ofwor k done 53 Character ofthe coals ---------------------------------------------­ 54 Analyses of samples 54 Ran k of coal ------------- 57 Fr ia bility _________ 57 Slac king character sticsi ______________ _ 58 Low temperature carboni zat ion assay ____ _ 58 Hy drogenat io n ofcoal -------------------­ 60 Burn in g tests --------------------------- ------------- 60 Summary ______________ _ _____________ _ 61 Conclus ion s ____ --------------- 62 Fa ctors affe ct in g minab ility ofcoals _ 62 Th ickness ---------------------------------------- --------------- 62 Part ings __ 63 Att itude _______ _ 63 Roo f and fl oor _ 63 Cleavage _________ _ 63 Dra inage _____ _ 63 Gas ----------------- 63 Transportat oni 64 v CONTENTS-Continued Page Description ofcoal mines and prospects -------------- ------------------------------------- ------------------------ 64 Introduction ------------------------------------------------------------------------------------------------------------------------ 64 List ofmine numbers -------------------- ------------------------------------------------------------------------- 64 Upper coal group --------------------- ------------------------------------------------------------------------------------------ 67 North Bend basin coals -------------------------- - ------------------------------------------------------------------ 67 1. Wilcox mine ____________________ ______________________ --- ---------------------------------------- ------------- 67 Newport basin coals ______________________ ---------------- -------------------------------------- 69 2. Libby mines ·_____ ____ ______________ __________________ ------------------------------------------------------- 69 . 3. Englewood mines and pro ject ______ __ ------------------- ----------------------------------- -- 72 4. Reservoir mine ______________ _ ____________________ --------------------------------- 78 5. Fl anagan mine ________________ --------------------------------------------------------- - 80 Beaver Slough basin coals (west side) -------------------------------------------------------------------- 80 6. Southport mine and pro je ct -------------- -------------- ------------------------------------------- 80 7. Thomas mine ------------- ----------------------------- ------------------------------------------------- 83 8. Maxwell mine ----------------------- ------------------- ------ - --- ------------------------------------ 84 9. He nryville mine ________________ ___ _________________ _________________ ------------------------------------- 84 10. Delmar mines --- -------------------- ------------------------- 86 11. Overland mine _______ _ __________________ ------------------------------- 88 12. Martin mine __________________ _ _ _ __ _ ___ ------------------ ------------------ 90 13. Beaver Hi ll mine ________________ ----------------------------------- 92 14. Klondi ke mine - -------------------------- ------------------------------------- 96 15. Fa hy-M uir coals _________ ________________ _ __ ___________ ----------------------------- 97 Riverton basin coals (south