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1/25/2010 7:13:06 PM
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Title
River-Derived Slackwater Sediments in Caves along Cheat River, West Virginia
Date
3/28/1996
Prepared By
Elsevier Science Publishers
Floodplain - Doc Type
Educational/Technical/Reference Information
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<br />1 <br />, <br /> <br />s inside <br />.:ave. <br />c refuse <br />~unts of <br />jebris is <br />n inside <br />rash can <br />passage <br />is styro- <br />d on the <br />~ incon- <br />"lY water <br />organics <br />evidence ; <br />t not for ': <br />md silts <br />,w from <br />5.5 cm <br />The silts <br />mt mac- <br />op sedi- <br />lick mat <br /> <br />;-92-9 <br /> <br />m <br /> <br />n 05-92-9 <br /> <br />Stratigraphic Column GS-92-26 <br /> <br />G.S. Spring", J.S. Kite/Geomorphology 18 (J997i 91-100 <br /> <br />97 <br /> <br /> <br />o <br /> <br />20 <br /> <br />o <br />< <br />'" <br />a- <br />~ <br />~ <br />'" <br />en <br />'" <br />c., <br />'3 <br />'" <br />~ <br />;; <br /> <br />nizes 1 m of sediments deposited during the 1985 <br />flood but no deposits definitively assignable to pale- <br />ofloods. He concludes that the preservation potential <br />of surficial slackwater sediments is low because of <br />biogenic and weathering phenomena. <br />Slackwater deposits of the 1985 flood are pre- <br />served in the caves of the Cheat River canyon; <br />nonetheless the potential for preservation is low. For <br />optimum preservation, the cave must act as an effec- <br />tive shield from water and organisms. All of the <br />caves inundated by the 1985 flood receive water <br />from the overlying valley-wall. The caves are gener- <br />ally shallow, lying ,,10 m beneath the valley wall. <br />The sediments are not immune from biogenic alter- <br />ation because they may be penetrated by roots and <br />burrowing organisms and are physically removed <br />from the caves by stream flow. <br />Of the ten caves inundated by the 1985 flood, six <br />display slackwater sediments. Of the six, only two <br />cpntain fine-grained slackwater sediments; faunal <br />bioturbation was observed in these sediments. The <br />paucity of fine-grained sediments is attributable to <br />water from the overlying slopes. Fine-grained sedi- <br />ments persist only in sites not subject to scour by <br />water entering via joints in the ceiling. As the small <br />areal extent of overbank deposits in Figs. 3 and 4 <br />suggest, few parts of the caves do not receive water <br />from above. Sediments beneath ledges are not en- <br />tirely protected. Water entering a dome in Coliseum <br />Rapids Cave from a I hr duration, 7.5 cm rainfall <br />event was observed to flow down overhanging cave <br />walls and fall on the sediments of section GS-92-9 <br />(Fig. 4), 1-to-3 m from the edge of a ceiling ledge. <br />Woody debris, the largest component by volume <br />of the 1985 overbank deposits, is still present be- <br />neath domes of Coliseum Rapids Cave because cave <br />stream discharge is ineffective at moving large wood <br />particles (2-t0-2oo em in length). Vadose recharge, a <br />relative humidity of - 95%, and the constant year- <br />round temperature of - 120C in the cave maintain <br />an environment in' which decay of woody flotsam is <br />fostered. Continued decay will probably destroy the <br />wood debris within 25 years of the 1985 flood, <br />Woody flotsam deposited on the surface appears <br />considerably less decayed than that in the cave. The <br />plastic and styrofoam componenl. however, is largely <br />unaltered and will probably be preserved for cen- <br />turies. <br /> <br />I <br />'! <br /> <br /><J) <br />0:: <br />W <br />lii 40 <br />:: <br />;:: <br />z <br />w <br />060 <br /> <br />Texture Key: <br />~: 1 Sandy Loam <br />B Sill Loam <br />fBj <br />~ Fine Gravel <br /> <br /> <br />.... ... "":'" <br />..:~,~:~ <br />.;'.~~ <br /> <br />80 <br /> <br />Fig. 5. Stratigraphic column GS-92-26 from Cornwell Cave. <br />Slackwater sediments are deposited parallel to surfaces of deposi- <br />tion. Fine gravels from cave infeeders mantle scour surfaces. <br /> <br />of decomposing organics separate the two deposits. <br />The mat is heavily infested by fungal mycelia. Silts <br />are not present were water enters the cave from the <br />terrace, although flotsam is present beneath several <br />of these domes. <br />Cornwell Cave: This large maze cave lies 38-to-40 <br />m above Cheat River. Overbank sediments consist of <br />unconformity-bounded loamy silts interbedd.ed with <br />clast-supported fine gravels derived from small <br />streams entering the cave via vertical domes (Fig. 5). <br />The silts display inclined laminar bedding. The dip <br />direction of laminae is markedly different across the <br />gravel interbeds. As many as five distinct paleoflood <br />units are present in a single stratigraphic column <br />(Fig. 5). <br />The loamy silts were deposited during infrequent <br />flooding of Cheat River, and later eroded by vadose <br />streams. Subsequent flooding resulted in parallel ac- <br />cretion of loamy silts on scour surfaces. Parallel <br />accretion is common in the cave environment and is <br />documented only in pipe-full passages. <br /> <br />6. Preservation of sediments <br /> <br />Linton (1992) examines slackwater deposits in the <br />tributary mouths along the Cheat River narrows be- <br />tween Rowlesburg and Albright (Fig. 1). He recog- <br />
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