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.. 98 G.S. Springer. 1.5. Kite jGeomorphoJogy 18 (J997) 9J-JOO The poor preservation of 1985 slackwater sedi- ments contrasts with the excellent preservation of paleoflood sediments in Cornwell Cave. Interpola- tion, using a 59 mm/ka incision rate calculated by Springer (J 994) for Cheat River, indicates that the sediments are > 400,000 yr old. The contrasting preservational potential of the two sets of slackwater sediments is a direct product of different geomorphic settings. The majority of Cornwell CjlYe is .-Overlain by 20-to-30 m of limestone and shale. The caprock limits recharge to the cave and favors preservation of sediments. The caves of lower Coliseum Rapids are overlain by :;; 10 m of colluvium, alluvium, and bedrock that readily transmit recharge to the caves and, hence, promote erosion of slackwater sedi- ments. 7, Potential use for hydraulic reconstructions * Flood slackwater sediments indicate peak stage from which the discharge of a flood can be calcu- lated using hydraulic reconstruction methods and the Manning equation (Patton et al., 1979). Knowing the crOSS-SectiODal area of the peak flow channel, chan- Del gradieDt, and channel roughness coefficieDt, flow velocity and discharge may be calculated. LiDton (1992) uses this method to independently calculate discharge values based on the maximum heights of slackwater sediments and high water marks. Linton reports that slackwater sediments deposited by the Cheat River. flood in tributary mouths are 2.9 to 5.6 m below high water marks. High water marks indi- cate peak stage water depths of 6 to I I m. The difference between high water marks and slackwater sediment beigbts represents a substantial fraction of the total flood depth, therefore, calculations based on 1985 flood slackwater sediments underestimate peak discharge of Cheat River by 50% relative to high water marks. Linton reports that flotsam, the most common high water mark, is an accurate indicator of peak stage, but flotsam is unlikely to be preserved in the geologic record because of decay. The uppermost slackwater sediments in caves of the Cheat River canyon lie within I m of the upper- most flotsam. This narrow gap between the high water mark and slackwater sediments contrasts with elevation differences of greater than 2.9 m observed by Linton (1992). The narrow gap suggests that sediments within the caves of Cheat River canyon are accurate indicators of peak flood stage heights and could be used to more accurately calculate flood discharge values. Hydraulic reconstructions were not performed us- ing the ] 985 slackwater sediments in caves of lower Coliseum Rapids. The hydraulic gradient was signifi- cantly steepened at the downstream terminus of Lower Coliseum Rapids during the 1985 flood. This invalidates the slope-area method. Modeling of dis- charge using the step-backwater method was beyond the scope of this paper. 8, Discussion The cave overbank facies is composed of three subfacies: loamy silts, very fine sands, and flotsam. In addition to flotsam, Kite and Linton (1993) and Linton (1992) recognize four textural units in sedi- ments deposited by the 1985 flood in the Cheat Narrows: basal gravel and sand, sandy loam, silt loam, and fine sandy loam. The sandy loam (Linton's unit B) is the most commonly encountered deposit in tributary mouths and is interpreted to represent depo- sition by the tributary. Linton (1992) reports that of the four units, only the silt loam was deposited by Cheat River. The silt loam observed in caves of lower Coliseum Rapids is similar to the silt loam observed by Linton (1992). Both are blanket-like deposits with abundant organic matter and each is interpreted as a slackwater deposit Very fine sands and loamy sands observed in Colluvium Breath Cave are not analogous to Linton's (1992) sandy loam. Linton reports that the sandy loam thins away from tributary channels and proba- blyrepresents deposition by tributary floodwaters, prior to ponding of the tributary by Cheat River. The sandy loam observed in Colluvium Breath Cave is not, however, associated with any recharge point except the southwestern entrance of the cave. There- fore, the sandy loam represents deposition by flood- waters of Cheat River. The sands of ~ Colluvium Breath Cave may be analogous to the small sand deposits Linton (1992) found between boulders. Be- cause of different settings, the deposits in the cave are of broader extent T Exc. into lhi periods the caVI does rei the non pathwa~ The lac screenir of clast Hence, as tribu! in cave~ sedimen To e mouths (1993) charge When 11 tributari mass. A tween tl signific. River \\ sedimen suIted ir of peak 1993).1 flood pe because discharg create a slackwal (1993) . in cav~ precise i Thed stage w: COnsiS1el (1982), : (1979). : Were de tained P' sedimen1 caves th this stud ments fr The I