- • .JI April 1981 Volume 9 Number 2 WASHINGTON GEOLOGIC NEWSLETTER The Washington Division of Geology and Earth Resources staff-The people who serve you ( see inside cover for identification) &RIAN J. &OYLE COMMISS IONER OF PUBLIC LANDS RALPH A. IIESWlCK, Supervisor VAUGHN E. LIVINGSTON, JI!., Stole Geologist DEPARTMENT OF NATURAL RESOURCES DIVISION OF GEOlOGY ANO EARTH RESOURCES Cheney office See the numbers below to identify us. 1. Henry W. Schasse 8. Janet Miller 15. Arnold Bowman 22. J. Eric Schuster 2. Ted Livingston 9. Loretta Andrake 16. Mike Korosec 23. Carl R. McFarland 3. Keith Ikerd 10. Wanda Walker 17. Nancy Herman 24. Glennda B. Mclucas 4. Timothy J. Walsh 11. Connie Manson 18. Wayne S. Moen 25. Mark Macleod 5. James G. Rigby 12. Allen J. Fiksdal 19. Ellis R . Vonheeder 26. Gerald W. Thorsen 6. Josh Logan 13~ Weldon W. Rau 20 . Laura Bray 27. Pamela Whitlock 7. William Phillips 14. Anne Curtis 21. Dorald M. Ford 28 . Keith Stoffel 29 . Bonnie Bunning Mort in Way 1- 5 ... io Por,1ond Exit 108 '·: GEOLOGY AND / t South EART~~: i!--L-..L.L.L..L"'-1 I Sound t : "'~ ,.; · ..__ ___._ Moll ___ Poul,oni ~••.•••• Park .ing ......7 0 St. Martini Coll•o• 6th Allt. Mailing address: Department of Nat ural Resources Field of(ic:e ,1ddress: Department o{ Natu ral Resources Divl11lon o( Geology and Earth Resources Division of Geology and Earth Resources Olympia, WA 98504- Senior Hall, Eastern Washington Univer slty Cheney, WA 99004 (l06) 753-6183 (509) 359-2278 The Washington Geologic Newsletter, a quarterly report of geologic articles, is published by the Division of Geology and Earth Resources, Department of Natural Resources. The newsletter is free upon request. The division also publishes bulletins, Information circulars, and geologic maps. A list of these publications will be sent upon request. COAL GEO LOGY OF KI NG COUNT Y, WASHINGT ON by William M. Phillips and Timothy J. Walsh Washington State coal 1·eserves were Creek to Lake Sammamish, to Lake Washington, estimated in 1961 to be about 6 billion tons down the Black River to the Duwamish River, ( Beikman and others, 1961) . On the basis of and finally to port. Coal was discovered at this estimate, the King County coal fields con­ Coal C1·eek short1y thereafter , and it a1so went tain about 15 percent of the total state reserves to market by this circuitous route. Development and one-third of the bituminous reserves. proceeded slowly, however , until the first rail­ While reserve figures will change substantially road in the Puget Sound region was completed as bedrock below the extensive glacial cover in 1872. Coal exports leaped from 4 , 918 tons of western Washington is explored, it is ap­ in 1871 to 14,830 tons in 1872, and by 1879, parent that King County contains one of the exports were up to 132,263 tons. Of the major coal deposits in the state. Coal re.sources 790,639 tons exported during the decade, io King County were last studied about a decade 733, 794 tons were produced at the Newcastle ago (Vine, 1969; Livingston, 1971). Since that mines, the i·emainder coming from the Renton time, new information has become available. In area mines (Bagley, l 929). addition, King County is rapidly becoming In 1880, the San Francisco-based Black urbanized. Detailed coal resource and mining Diamond Company sent an expedition to Wash­ information is needed fo1· the basis of land-use ington to explore for a better coal than that decisions. The authors are currently engaged being shipped from Newcastle. In July of that in a study of King County coal which will up­ year, they discovered I.he coal of the Franklin date reserve and resource figures and define coal zone along the Green River. The lower the location and extent of past mining activities. quality coals of the superjacent Kummer coal zone of this area had been known since 1873, COAL MI N I NG H ISTORY but had not as yet been mined ( Thorndale, 1965) . There was limited production at Franklin Coal was first discovered in King County and Black Diamond by 1883, and with the com­ in 1853 by Dr. M. Bigelow while he was clear­ pletion of the rail Jin k to Seattle in 1885, the ing his land near what is now Renton. Such Green River district soon became the major was the demand for energy that Bigelow's coal coal-producing region on the Pacific coast. It fetched a delivered price of $30 per ton in reached a peak annual production of 925, 000 San Francisco (Bagley, 1929). ln 1861 L. B. tons in 1903. and more than half of all the coal Andrews discovered coal on a hillside just west mined in King County to date has been from of the present city of lssaq uah. Because there the Green River district (Beikman and others, were no roads connecting the discovery to a 1961). port, this coal had to be barged down Issaquah With the development of Califo1·nia oil at the turn of the century, de mand for King Important stratigraphic differences exist County coal waned. From a peak of 1. 45 mil­ between the north and south coal-bearing areas lion tons in 1907, King County production (fig. 2). In the south, the oldest e xposed declined steadily. Today only a single mine rocks belong to the Puget Group, a sequence near Black Diamond remains in operation with of non marine deltaic sandstones, shales, and 1980 production of only 6,000 tons. coals. About 6, 200 feet of the Puget Group is well exposed in the canyon of the Green River. STRATIGRAPHY The Green River section contains 55 percent feldspathlc or arkosic sandstone, 35 percent The coal fields of King County may be siltstone. and 10 percent shale. carbonaceous conveniently grouped into two areas: the shale, and coal. Significant quantities of Newcastle Hills-Cedar Mountain- Taylor area to v olcaniclastic rocks or lava flows a.re entirely the north and, to the south, the Green River a bsent except in the uppermost 350 feet of the fields (fig . 1) • The Cedar River drainage is section where volcanic debris interfingers with an approximate dividing line between the two arkosic sandstones (Vine, 1969). The coal beds areas. are the most useful stratigraphic markers in R6E R8E T24N LEGEND cool- bearing areo / onticlinol a•is showing plunge T22N T22N /- synclfnot o•1s showing plunge -- - fault cool prospect 11 2~0000 0 5ml T2tN Ar~ ot )a t l)lf mop T21N ' .. , ... ;:----- RSE R6E R7E R8E F1GURE 1.-Major coal-bearing areas of King County . Major folds, faults, and coal prospects a r e also shown. 2 STRATIGRAPHY s.,, .. t:lorol 1too11 ot Or etn R 10 , Canyon or•o Tl•tr Mounta in -To1lor Wolle !1969) hleYn1C11n orto + + ftu1mcla• 'or"'otlon ot H•,nmo"d (196S) + + + + + \lpptr + + + + - + + + + + + + + + + ++ + + + + + 011, ..... """'"'... itn IO•lr Kunu'l'l e, ,ondttof'I• btd R• nton Form o,ton '-?-? + upper Gt '" coot r. • d ! ~+ + -+ + "'. ~ Tu•w oo FormoHon + Rovtnton ...____ i -.cKoy coot btd g + + + + low,, '.~Q. + + i B!Q 0Hty COO i b.cl Eoc,n, : e Ti9tr Moul'\ta1n Forma tion up;iitr .. fuho"lon ...____ . > IOW H .. -- -- Fronlllln No, 12 t<>ol btd - -- - A:oolnq River For moflon - -- -- ~- - f,..,•11~ No. 10 cool-.~ - ---- _. - - '-" """ Fro n 11.lln\011 ---- - - Bott not tlPOHd 8011 c.ov ,r•d F-1 E:±..±.l mori11e aed irn ento ry volcanic rocks non morfne 11dimentory rocks rocks FIGURE 2 . - Correlation of the Puget G1·oup in the Green River Canyon area and equivalent rocks in the Tiger Mountain-Taylor Mountain area (after Vine, 1969). the section. Previous workers (Evans, 1912; claw Formation of Hammond, 1963). Fossil Weaver, 1937) divided the Green River section leaves (Wolfe, 1968) indicate that the overlying into II series II and formations but these sub­ volcanics are in part early Oligocene. divisions are not mappable outside the immediate To the north, in the Tiger Mountain­ vicinity of the Green River section (Vine, 1969). Taylor Mountain uplands, the oldest exposed Abundant fossil leaves are present in the rocks belong to the m~ine Raging River For ­ Puget Group of the Green River area. On the mation (Vine, 1962). It is composed of as much basis of floral megafossils, Wolfe (1968) found as 3,000 feet of dark-gray sandstone; siltstone, the Green River section to range from early and claystone, largely of volcanic origin. On Eocene to early Oligocene age. Recent work the basis of foraminiferal assemblages, the Rag­ (Triplehorn and others, 1980) based upon the ing River Formation is assigned a middle Eocene dating of volcanic ash partings from G!'."een age (Wolfe , 1968) . It is gradationally overlain River coals suggests that the 6,200 feet of by the continental Tiger Mountain Formation, section is entirely late Eocene. which is composed of about 1,100 feet of sand­ The Puget Group is overlain with slight stone, shale, and coal. In the superjacent 1,700 or no unconformity (Warren and others, 1945; feet, Tiger Mountain Formation is interbedded Vine, 1969) by a sequence of continental lava with epiclastic volcanic rocks of the Tukwila and breccia flows with subordinate tuff, tuff­ Formation . The main body of Tukwila F orma­ breccia and volcanic sedimentary rocks (Enum- tion, as much as 8,000 feet thick neai· Issaquah, 3 overlies this interstratified zone. Vine (1969) coal fields are dominated by northwest-trending correlates these rocks with the Fultoniau and folds. At the Newcastle Hills and to the east, Ravenian stages of the Green River section the folds plunge to the northwest.